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Oracle - SQL - Alter Table
 
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Oracle - SQL - Alter Table Watch more Videos at https://www.tutorialspoint.com/videotutorials/index.htm Lecture By: Mr. Anadi Sharma, Tutorials Point India Private Limited.
Oracle SQL Tutorial 21 - How to Create / Drop Indexes
 
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In the last video, we wrote up the SQL to create three tables: CREATE TABLE users( user_id NUMBER, username VARCHAR2(50 CHAR) UNIQUE, CONSTRAINT users_pk PRIMARY KEY (user_id) ); CREATE TABLE projects( project_id NUMBER, Project_name VARCHAR2(50 CHAR) UNIQUE, creator VARCHAR2(50 CHAR) NOT NULL, CONSTRAINT projects_pk PRIMARY KEY (project_id), CONSTRAINT projects_users_fk FOREIGN KEY (creator) REFERENCES users (username) ON DELETE CASCADE ); CREATE TABLE project_users( project_id NUMBER NOT NULL REFERENCES projects (project_id) ON DELETE CASCADE, user_id NUMBER NOT NULL REFERENCES users (user_id) ON DELETE CASCADE, CONSTRAINT project_users_pk PRIMARY KEY (project_id, user_id) ); I'm going to increase the size of the users table a bit by adding a first and last name column. CREATE TABLE users( user_id NUMBER, username VARCHAR2(50 CHAR) UNIQUE, first_name VARCHAR2(50 CHAR), last_name VARCHAR2 (50 CHAR), CONSTRAINT users_pk PRIMARY KEY (user_id) ); But before we finish this design, we should consider indexing certain columns. What columns should we index? Well, as a reminder, the columns that are indexed by default are columns with the UNIQUE constraint, and those that are labeled as primary keys. Columns that are not indexed but often should be are those labeled as a foreign key. The column that jumps out the most to me is the creator column of the project table. It's the only foreign key that is not part of some index. Let's fix this by creating our first index. The way we do that is with the CREATE INDEX command. CREATE INDEX projects_creator_ix ON projects (creator) What naming convention are we following for the index? We are naming it by the table name, followed by an underscore, followed by the column, followed by an underscore, followed by an ix (for index). In this situation it does not apply, but if our foreign key column is labeled as UNIQUE, we can add the UNIQUE keyword like this: CREATE UNIQUE INDEX projects_creator_ix ON projects (creator) Now if you want to get rid of an INDEX, you can use this command: DROP INDEX projects_creator_ix Now, if we want to select data from the user table and the project table we can do that much faster. That's because the foreign key and column it references are both indexed and those are the columns we would do the join on. We will discuss how to do joins in a future video. So what are some potential problems with this database design? Overall, it is pretty good. With this design though we need to make sure there is no way for someone to update a user's username. In the next video we are going to discuss why. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Support me on Patreon! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://bit.ly/JoinCCNewsletter Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://twitter.com/calebCurry Amazing Web Hosting - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 10186 Caleb Curry
How To Add New Column(Field) in Existing table Using Oracle Database
 
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In this video You will learn how to Add new column after creating a new table or existing tables in oracle database , This video help us adding one or more than columns as per project requirement. add a column add a column in a table add a column in sql add a column in table add a column sql add a column to a table add a column to an existing table add a column to sql table add a column to table add a new column add column add column alter table add column in a table add column in a table oracle add column in existing table add column in oracle add column in sql add column in table add column in table oracle add column in table sql add column into table add column ms sql add column oracle add column oracle sql add column oracle table add column pl sql add column sql add column sql oracle add column sql script add column sql server add column sql server 2008 add column sql server 2012 add column table add column table oracle add column to a table add column to a table sql add column to database add column to existing table add column to existing table sql server add column to oracle table add column to sql add column to sql server table add column to sql table add column to table add column to table oracle add column to table sql add column to table sql server add column to table sql server 2008 add column tsql add field sql add field sql server add field to table sql add new column add new column in existing table add new column in oracle database tables add new column in table sql add new column sql add new column to sql table add new column to table add new column to table oracle add new column to table sql add sql column add table column add to table sql alter a table sql alter table alter column sql alter table change column sql alter table column sql alter table command sql table add column sql table alter sql update table add column sql update table column sqlplus alter table table add column table alter table columns add update add column update column oracle update table add column update table add column oracle update table add column sql
Views: 2856 Programming Lifestyle
SQL Server 34 - How to Create and Drop Indexes
 
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Creating indexes is a very easy task, but before you go creating indexes on everything, you need to know that some columns are indexed by default. Specifically, any column that is labeled as the PRIMARY KEY or UNIQUE are indexed by default. That means that if you have a UNIQUE column, you do not need to worry about adding an INDEX to it. The columns that you will want to pay special attention to are any foreign keys or columns that you are going to use very frequently. We are going to create an index on our SpeciesID column in our Animals table. This is a foreign key that I'm likely going to use very frequently. CREATE INDEX IX_AnimalsSpecies ON Animals (SpeciesID); The syntax is very similar to CREATE TABLE in that you say CREATE INDEX followed by an index name. The IX_ is a prefix that is sometimes conventionally used to name indexes. Next, we have the table name, and then we have something to describe the column. That way if you see IX_AnimalsSpecies, you automatically know it is talking about an Index for the Animals table that is on the column dealing with the species. To get rid of this index, use this: DROP INDEX IX_AnimalsSpecies; Which is also very similar to how we drop a table. Now, you can also create an INDEX on multiple columns if you are going to use them together very often. The way you do that is just add another column after a comma inside of the () in the index columns. For example: CREATE INDEX IX_AnmialsContact ON Animals (Name, ContactEmail); One other thing I wanted to show you is that you can actually create a UNIQUE Index by adding the keyword in: CREATE UNIQUE INDEX IX_Species ON Species (Species); This should only be used if every value for a column is labeled unique…In fact, it forces every row to be unique. Remember though that if a column is labeled UNIQUE, it is indexed by default...So this is not needed in this situation. In the next video we will discuss in more detail whether you want to use the UNIQUE Constraint create a UNIQUE index. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Support me! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://bit.ly/JoinCCNewsletter Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://twitter.com/calebCurry Amazing Web Hosting - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 10715 Caleb Curry
SQL with Oracle 10g XE - Using ALTER TABLE to Modify Table Columns
 
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In this video I use the ALTER TABLE command to modify an existing field column. The command will allow you to change the data types, whether the field can be null, or even the primary key. When using the ALTER TABLE command you would use the keyword MODIFY to make changes to an existing column. Be careful when changing a data type of the null field as existing data may cause an error if not in compliance with the new change. The code I used to alter the Books table is : ALTER TABLE BOOKS MODIFY ISBN_10 VARCHAR(13); This video is part of a series of videos with the purpose of learning the SQL language. For more information visit Lecture Snippets at http://lecturesnippets.com.
Views: 16417 Lecture Snippets
[Modifying Indexes] 1 - Modifying an index using the ALTER INDEX statement
 
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Modifying Indexes Given SQL Server tables named Customer_Details and XMLDocument in ABC_Bank database,you will view and practice how to create and modify an index using Transact-SQL commands. 1 - Modifying an index using the ALTER INDEX statement 2 - Create an XML index 3 - Modifying an XML index using ALTER INDEX command. Learn more and source code at : http://www.tutorialspoint.edu.vn/sql-server/163-maintaining-indexes/12611-workshop-maintaining-indexes.html
Views: 507 little fire
[Modifying Indexes] 3 - Modifying an XML index using ALTER INDEX command
 
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Modifying Indexes Given SQL Server tables named Customer_Details and XMLDocument in ABC_Bank database,you will view and practice how to create and modify an index using Transact-SQL commands. 1 - Modifying an index using the ALTER INDEX statement 2 - Create an XML index 3 - Modifying an XML index using ALTER INDEX command. Learn more and source code at : http://www.tutorialspoint.edu.vn/sql-server/163-maintaining-indexes/12611-workshop-maintaining-indexes.html
Views: 217 little fire
SQL tutorial 61: SEQUENCE in Oracle Database By Manish Sharma RebellionRider
 
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This tutorial is all about Sequence In Oracle Database. In this SQL Tutorial you will learn How to create a sequence How to populate a Primary key column (auto increment in Oracle) using Sequence How to drop a sequence ------------------------------------------------------------------------ ►►►LINKS◄◄◄ Blog : http://bit.ly/sql-sequence-in-oracle-database-rebellionrider-manish-sharma Previous Tutorial ► How To Insert Data into Table using SQL Developer http://youtu.be/YYQCSV6MzTk ► INSERT INTO Command http://youtu.be/uQXgqFtxI_k ► How to copy /Insert data into a table from another table http://youtu.be/m3Ep8tAMqok ------------------------------------------------------------------------- ►►►Help Me In Getting A Job◄◄◄ ►Help Me In Getting A Good Job By Connecting With Me on My LinkedIn and Endorsing My Skills. All My Contact Info is Down Below. You Can Also Refer Me To Your Company Thanks ------------------------------------------------------------------------- Copy Cloud referral link || Use this link to join copy cloud and get 20GB of free storage https://copy.com?r=kb4rc1 -------------------------------------------------------------------------- ►Make sure you SUBSCRIBE and be the 1st one to see my videos! -------------------------------------------------------------------------- Amazon Wishlist: http://bit.ly/wishlist-amazon ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ►►►Find me on Social Media◄◄◄ Follow What I am up to as it happens on https://twitter.com/rebellionrider https://www.facebook.com/imthebhardwaj http://instagram.com/rebellionrider https://plus.google.com/+Rebellionrider http://in.linkedin.com/in/mannbhardwaj/ http://rebellionrider.tumblr.com/ http://www.pinterest.com/rebellionrider/ You can also Email me at for E-mail address please check About section Please please LIKE and SHARE my videos it makes me happy. Thanks for liking, commenting, sharing and watching more of our videos This is Manish from RebellionRider.com ♥ I LOVE ALL MY VIEWERS AND SUBSCRIBERS
Views: 46237 Manish Sharma
Oracle Database SQL Tutorials 29 :: How to Alter Statement  using SQL ,Add Constraint,column
 
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www.facebook.com/oracle.shohag Email : [email protected] Website : www.oraclebangla.com Topics : How to Alter Statement Object Structure using SQL ,Add Constraint,column add Oracle Database SQL Tutorials | how to Alter a table structure using SQL | Oracle Bangla 2017 How to alter a Table Structure using SQL | Alter statement | SQL tutorials | Oracle Bangla 2017 | HD Oracle SQL Tutorials. how to alter a table using sql
Views: 1278 Oracle Bangla
auto increment in sql oracle - ( Auto increment field )
 
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auto increment in sql oracle ----------------------------------------------- CREATE table customers ( customer_id int not null, customer_name varchar(50), primary key (customer_id) ); create sequence customer_id minvalue 1 start with 1 cache 10; insert into customers values(customer_id.nextval,'maxwel'); -- to drop sequence drop sequence customer_id
Views: 9992 Data Disc
How to create Unique Constraint on Column for already existing Table - Part 97
 
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SQL Server / T-SQL Tutorial Scenario: You are working as SQL Server developer, you need to create Unique Constraint on already existing table called dbo.Customer on column SSN. Link to scripts used in SQL Server / TSQL Tutorial Video http://www.techbrothersit.com/2016/05/how-to-create-unique-constraint-on_6.html Check out our website for Different SQL Server, MSBI tutorials and interview questions such as SQL Server Reporting Services(SSRS) Tutorial SQL Server Integration Services(SSIS) Tutorial SQL Server DBA Tutorial SQL Server / TSQL Tutorial ( Beginner to Advance) http://www.techbrothersit.com/
Views: 1201 TechBrothersIT
Oracle tutorial : What is Virtual column in Oracle PL SQL
 
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This video will show you " Oracle tutorial: What is Virtual column in Oracle PL SQL " sql calculated field computed column oracle-11g-new-feature-virtual-column Oracle tutorial : What is Virtual column in oracle Syntax : column_name [datatype] [GENERATED ALWAYS] AS [expression] [VIRTUAL] 1)The values of the virtual column are not stored in the database. 2)You can not update the values of virtual column. 3)when you try to modify it will give oracle error. 4)These are read only values. 5)Virtual columns used in the WHERE clause of UPDATE and DELETE statement 6)Constraints can be created on them. #techquerypond https://techquerypond.wordpress.com https://twitter.com/techquerypond
Views: 1565 Tech Query Pond
SQL @ Owenskie: ALTER TABLE
 
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Add and Remove columns in a table using ALTER TABLE
Views: 1014 owenskie2010
Oracle SQL 08 How to Adding a column to a table
 
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USING SQL COMMAND Types of SQL Commands The following sections discuss the basic categories of commands used in SQL to perform various functions. These functions include building database objects, manipulating objects, populating database tables with data, updating existing data in tables, deleting data, performing database queries, controlling database access, and overall database administration. The main categories are DDL (Data Definition Language) DML (Data Manipulation Language) DQL (Data Query Language) DCL (Data Control Language) Data administration commands Transactional control commands Defining Database Structures Data Definition Language, DDL, is the part of SQL that allows a database user to create and restructure database objects, such as the creation or the deletion of a table. Some of the most fundamental DDL commands discussed during following hours include the following: CREATE TABLE ALTER TABLE DROP TABLE CREATE INDEX ALTER INDEX DROP INDEX CREATE VIEW DROP VIEW Manipulating Data Data Manipulation Language, DML, is the part of SQL used to manipulate data within objects of a relational database. There are three basic DML commands: INSERT UPDATE DELETE Selecting Data Though comprised of only one command, Data Query Language (DQL) is the most concentrated focus of SQL for modern relational database users. The base command is as follows: SELECT This command, accompanied by many options and clauses, is used to compose queries against a relational database. Queries, from simple to complex, from vague to specific, can be easily created. The SELECT command is discussed in exhilarating detail during Hours 7 through 16. A query is an inquiry to the database for information. A query is usually issued to the database through an application interface or via a command line prompt. Data Control Language Data control commands in SQL allow you to control access to data within the database. These DCL commands are normally used to create objects related to user access and also control the distribution of privileges among users. Some data control commands are as follows: ALTER PASSWORD GRANT REVOKE CREATE SYNONYM You will find that these commands are often grouped with other commands and may appear in a number of different lessons throughout this book. Data Administration Commands Data administration commands allow the user to perform audits and perform analyses on operations within the database. They can also be used to help analyze system performance. Two general data administration commands are as follows: START AUDIT STOP AUDIT Do not get data administration confused with database administration. Database administration is the overall administration of a database, which envelops the use of all levels of commands. Database administration is much more specific to each SQL implementation than are those core commands of the SQL language. Transactional Control Commands In addition to the previously introduced categories of commands, there are commands that allow the user to manage database transactions. COMMIT Saves database transactions ROLLBACK Undoes database transactions SAVEPOINT Creates points within groups of transactions in which to ROLLBACK SET TRANSACTION Places a name on a transaction Transactional commands are discussed extensively during Hour 6, "Managing Database Transactions." sql interview questions,sql interview questions and answers,interview questions for freshers,SQL,sql tutorial BEGINNERS,oracle,pl sql,pl/sql,mysql,oracle interview,google interview question,trigger in oracle,dbms,rdbms, oracle tutorial,pl sql basics,pl sql tutorials, pl sql example,sql,sql server ,query,sql query,questions,interview questions,coding interview,sql coding, code , database interview questions and answers,interview questions sql, interview questions,sql server,sql interview,interview sql,interview question sql join ,inner join, group by,select sql,interview questions ,sql basic, PL SQL Programs,PL SQL,PL SQL block,PL SQL Function,PL SQL Package,PL SQL Package body,PL SQL Procedure ,PL SQL Trigger,PL SQLType,PL SQL Type body,CREATE OR REPLACE PROCEDURE,database interview questions and answers,interview questions sql, interview questions,sql server,Procedural Language,interview sql,interview question sql join ,inner join, group by,select sql,interview questions ,sql basic,pl sql variable,oraclecoach,claire rajan, PL SQL,PL SQL block,PL SQL Function,PL SQL Package,PL SQL Package body,PL SQL Procedure,PL SQL Trigger,PL SQLType,PL SQL
Oracle SQL Tutorial 14 - Column-Level and Table-Level Constraints
 
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In the previous video we talked about adding constraints at the column-level. We made it nice and simple by only requiring a few keywords, but the problem we were having is that we could not assign a name to the constraint, which many people like to do so we can reference easily if we need to at a later time. To do this, it requires a little bit more typing, but it will give us extra flexibility and many consider it to be the higher quality approach to adding constraints. Let's go though a simple example. Let's say we have a users table with a user_id column that we want to make a primary key. We will create the table like this: CREATE TABLE( user_ id NUMBER PRIMARY KEY ) Instead of adding the PRIMARY KEY keywords after the data type, we add: CONSTRAINT user_pk PRIMARY KEY Now, we have assigned the name user_pk to this constraint. You can do the same with other constraints, such as UNIQUE. The syntax would be CONSTRAINT username_un UNIQUE. The other way to create constraints requires to put all of our constraints at the bottom of our table creation rather than inline with the column. This type of constraint is known as a table-level constraints. To make a column a primary key using table-level constraints, we add it to the CREATE TABLE command as if it is another row and use the CONSTRAINT keyword to tell Oracle that what is coming is a constraint, not a column in our table. CREATE TABLE users( user_id NUMBER, username VARCHAR2(50 CHAR), CONSTRAINT username_un UNIQUE (username), CONSTRAINT users_pk PRIMARY KEY (user_id) ) The primary differences here is that you have to put the column you are talking about in parenthesis after the PRIMARY KEY keyword. That's because it's at the end of the table and you need a way to tell it what column you are talking about. The option of putting it at the end of the table has the added benefit in this situation because if we needed to have a primary key that is the combination of multiple columns, we can do that by just adding the other column in the PRIMARY KEY parenthesis right after a comma. In summary, there are three ways to make constraints. The first is at the column level, unnamed. The second is at the column level, named. The third is at the table level, also named. In the next video we are going to create a named constraint in Oracle SQL Developer, so stay tuned and be sure to subscribe! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Support me! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://bit.ly/JoinCCNewsletter Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://twitter.com/calebCurry Amazing Web Hosting - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 17957 Caleb Curry
010 MySQL Queries Alter Columns
 
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Alter Columns to add a column, add column at position, delete column, rename column, resize column and resize less than data store to generate error
Views: 108 Amit Agarwal
Oracle SQL 08 How to Adding a column to a table USING SQL COMMAND
 
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CREATE TABLE command in sql/oracle,INSERT command in sql/oracle UPDATE,ALTER PASSWORD command in sql, GRANT command, REVOKE command i, CREATE SYNONYM command in sql/oracle, DELETE command in sql/oracle, ALTER TABLE command in sql/oracle, DROP TABLE command in sql/oracle, CREATE INDEX command in sql/oracle, ALTER INDEX command in sql/oracle, DROP INDEX command in sql/oracle, CREATE VIEW command in sql/oracle, DROP VIEW command in sql/oracle, Types of SQL Commands The following sections discuss the basic categories of commands used in SQL to perform various functions. These functions include building database objects, manipulating objects, populating database tables with data, updating existing data in tables, deleting data, performing database queries, controlling database access, and overall database administration. The main categories are DDL (Data Definition Language) DML (Data Manipulation Language) DQL (Data Query Language) DCL (Data Control Language) Data administration commands Transactional control commands Defining Database Structures Data Definition Language, DDL, is the part of SQL that allows a database user to create and restructure database objects, such as the creation or the deletion of a table. Some of the most fundamental DDL commands discussed during following hours include the following: CREATE TABLE ALTER TABLE DROP TABLE CREATE INDEX ALTER INDEX DROP INDEX CREATE VIEW DROP VIEW These commands are discussed in detail during Hour 3, "Managing Database Objects," Hour 17, "Improving Database Performance," and Hour 20, "Creating and Using Views and Synonyms." Manipulating Data Data Manipulation Language, DML, is the part of SQL used to manipulate data within objects of a relational database. There are three basic DML commands: INSERT UPDATE DELETE These commands are discussed in detail during Hour 5, "Manipulating Data." Selecting Data Though comprised of only one command, Data Query Language (DQL) is the most concentrated focus of SQL for modern relational database users. The base command is as follows: SELECT This command, accompanied by many options and clauses, is used to compose queries against a relational database. Queries, from simple to complex, from vague to specific, can be easily created. The SELECT command is discussed in exhilarating detail during Hours 7 through 16. A query is an inquiry to the database for information. A query is usually issued to the database through an application interface or via a command line prompt. Data Control Language Data control commands in SQL allow you to control access to data within the database. These DCL commands are normally used to create objects related to user access and also control the distribution of privileges among users. Some data control commands are as follows: ALTER PASSWORD GRANT REVOKE CREATE SYNONYM You will find that these commands are often grouped with other commands and may appear in a number of different lessons throughout this book. Data Administration Commands Data administration commands allow the user to perform audits and perform analyses on operations within the database. They can also be used to help analyze system performance. Two general data administration commands are as follows: START AUDIT STOP AUDIT Do not get data administration confused with database administration. Database administration is the overall administration of a database, which envelops the use of all levels of commands. Database administration is much more specific to each SQL implementation than are those core commands of the SQL language. Transactional Control Commands In addition to the previously introduced categories of commands, there are commands that allow the user to manage database transactions. COMMIT Saves database transactions ROLLBACK Undoes database transactions SAVEPOINT Creates points within groups of transactions in which to ROLLBACK SET TRANSACTION Places a name on a transaction Transactional commands are discussed extensively during Hour 6, "Managing Database Transactions."
Oracle - SQL - Foreign Key Constraint
 
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Oracle - SQL - Foreign Key Constraint Watch more Videos at https://www.tutorialspoint.com/videotutorials/index.htm Lecture By: Mr. Anadi Sharma, Tutorials Point India Private Limited.
mysql tutorial for beginners (6/8) : Indexes
 
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mysql tutorial for beginners (6/8) : Indexes As things stand, the table students works and can be searched without problem by MySQL—until it grows to more than a couple of hundred rows, At that point, database accesses will get slower and slower with every new row added, because MySQL has to search through every row whenever a query is issued. This is like searching through every book in a library whenever you need to look something up. Of course, you don’t have to search libraries that way, because they have either a card index system or, most likely, a database of their own. The way to achieve fast searches is to add an index, either when creating a table or at any time afterward. But the decision is not so simple. For example, there are different index types such as a regular INDEX, PRIMARY KEY, and FULLTEXT. Also, you must decide which columns require an index, a judgment that requires you to predict whether you will be searching any of the data in that column. And even when you’ve decided that, you still have the option of reducing index size by limiting the amount of each column to be indexed. If we imagine the searches that may be made on the students table, it becomes apparent that all of the columns may need to be searched. Anyway, go ahead and add an index to each of the columns, using the commands: ALTER TABLE students ADD INDEX(name(3)); An alternative to using ALTER TABLE to add an index is to use the CREATE INDEX command. They are equivalent, except that CREATE INDEX cannot be used for creating a PRIMARY KEY CREATE INDEX surname ON students (surname(5)); DESCRIBE students; These commands create indexes on both the name and surname columns, limiting name index to only the first 3 characters, and surname index to the first 5 characters. For instance, when MySQL indexes the following name: SAFAA It will actually store in the index only the first 3 characters: SAF This is done to minimize the size of the index, and to optimize database access speed. DESCRIBE command shows the key MUL for each column. This key means that multiple occurrences of a value may occur within that column, which is exactly what we want, as name or surname may appear many times. You don’t have to wait, until after creating a table to add indexes. In fact, doing so can be time-consuming, as adding an index to a large table can take a very long time. Therefore, let’s look at a command that creates the table students with indexes already in place. CREATE TABLE students ( Id_studnet SMALLINT UNSIGNED NOT NULL AUTO_INCREMENT, name VARCHAR(10) NOT NULL, surname VARCHAR(20) NOT NULL, email VARCHAR(30) NOT NULL, INDEX(name(3)), INDEX(surname(5)), ,PRIMARY KEY(id_studnet),UNIQUE(email)); Another important index, PK, its single unique key for each student to enable instant accessing of a row. The importance of having a key with a unique value for each row will come up when we start to combine data from different tables. You can add PK, while you create the table at the first time, or later by issuing the following command: ALTER TABLE students ADD PRIMARY KEY(id_student); The last important index, FULLTEXT index Unlike a regular index, MySQL’s FULLTEXT allows super-fast searches of entire columns of text. It stores every word in every data string in a special index that you can search using “natural language,” in a similar manner to using a search engine. It’s not strictly true that MySQL stores all the words in a FULLTEXT index, because it has a built-in list of more than 500 words that it chooses to ignore because they are so common that they aren’t very helpful for searching anyway. This list, called stopwords, includes the, as, is, of, and so on. The list helps MySQL run much more quickly when performing a FULLTEXT search and keeps database sizes down. FULLTEXT indexes can be created for CHAR, VARCHAR, and TEXT columns only. A FULLTEXT index definition can be given in the CREATE TABLE statement when a table is created, or added later using ALTER TABLE (or CREATE INDEX). Adding a FULLTEXT index to the table students for the columns name and surname ALTER TABLE classics ADD FULLTEXT(name,surname); this index is in addition to the ones already created and does not affect them You can now perform FULLTEXT searches across this pair of columns. If you find that MySQL is running slower than you think it should be when accessing your database, the problem is usually related to your indexes. Either you don’t have an index where you need one, or the indexes are not optimally designed. Tweaking a table’s indexes will often solve such a problem. In the next tutorial, we will learn about, using FOREIGN KEY Constraints and how to join tables together. Subscribe for more: ---------------------------------------------------------------------------- https://www.youtube.com/subscription_center?add_user=saf3al2a SWE.Safaa Al-Hayali - saf3al2a
Views: 31175 Safaa Al-Hayali
61. ALTER TABLE for Adding Constraint in Column SQL (Hindi)
 
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Please Subscribe Channel Like, Share and Comment Visit : www.geekyshows.com
Views: 11009 Geeky Shows
Oracle - SQL - Not Null Constraint
 
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Oracle - SQL - Not Null Constraint Watch more Videos at https://www.tutorialspoint.com/videotutorials/index.htm Lecture By: Mr. Anadi Sharma, Tutorials Point India Private Limited.
Oracle - SQL - Primary Key Constraint
 
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Oracle - SQL - Primary Key Constraint Watch more Videos at https://www.tutorialspoint.com/videotutorials/index.htm Lecture By: Mr. Anadi Sharma, Tutorials Point India Private Limited.
Clustered vs. Nonclustered Index Structures in SQL Server
 
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Clustered and nonclustered indexes share many of the same internal structures, but they're fundamentally different in nature. Watch Microsoft Certified IT Professional Jon Seigel explain the similarities and differences of clustered and nonclustered indexes, using a real-world example to show how these structures work to improve the performance of SQL queries. Blog post on primary key vs. the clustered index: http://voluntarydba.com/post/2012/10/02/The-Primary-Key-vs-The-Clustered-Index.aspx CREATE INDEX statement reference: http://technet.microsoft.com/en-us/library/ms188783.aspx ALTER INDEX statement reference: http://technet.microsoft.com/en-us/library/ms188388.aspx Index navigation internals by example: http://sqlblog.com/blogs/paul_white/archive/2011/08/09/sql-server-seeks-and-binary-search.aspx Sample index data is from the AdventureWorksLT2008R2 sample database: http://awlt2008dbscript.codeplex.com/releases/view/46169 Visit my channel for more database administration videos: https://www.youtube.com/voluntarydba Subscribe to get notified about my latest videos: https://www.youtube.com/voluntarydba?sub_confirmation=1 Read additional content on my blog: http://voluntarydba.com Follow on Twitter: https://twitter.com/voluntarydba Like on Facebook: https://facebook.com/voluntarydba
Views: 314163 Voluntary DBA
MySQL - phpMyAdmin 4.5.1 Add UNIQUE Constraint To Existing Column
 
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Mysql statement Alter Table to adding a UNIQUE Constraint key to an existing column to avoid duplicate rows
Oracle - SQL - Create Table
 
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Oracle - SQL - Create Table Watch more Videos at https://www.tutorialspoint.com/videotutorials/index.htm Lecture By: Mr. Anadi Sharma, Tutorials Point India Private Limited.
10 SQL with Oracle 10g XE   Using ALTER TABLE to Modify Table Columns
 
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10 SQL with Oracle 10g XE Using ALTER TABLE to Modify Table Columns
Views: 52 Cambo Movies
TP Oracle - Les Fondamentaux SQL
 
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TP Oracle - Les Fondamentaux SQL, Action Select et ses clauses, Fonctions monoLignes, Aggrégations, Sous requetes, Action DML (Insert, Update, Delete, Truncate, Merge, ...), Action DDL, Create User, Create Table, Create Index, Alter User, Alter Table, ..
Views: 1380 Mohammed Qbadou
MySQL alter table drop index
 
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MySQL alter table drop index, borra el indice asociado a una tabla
Views: 1033 Francisco Arce
CREATE TABLE WITH CONSTRAINTS - ORACLE - SQL
 
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Create table , add constraints : primary key constraint, foreign key constraint, check constraint, unique constraint, specifying the table space for index, modifying table, dropping table Oracle 10g
Views: 10042 R.N.A. Creation
Table Partitioning in Oracle Sql|Hash Partitioning|Range Partitioning|List Partitioning|Partitioning
 
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Table Partitioning in Oracle Sql | Hash Partitioning | Range Partitioning | List Partitioning | Partitioning --------------------------------------------------------------------------------------------------------- hash partitioning,range partitioning,oracle hash partitioned index example,partition by range interval,when to use range partitioning,what is table partitioning,list partitioning,how to query partition table in oracle,partition, sql server, sql, partitioning in oracle, hash, performance, oracle, partitioning, list, range, interval partition, reference partition, composite partition, index partition, partition pruning, table partitioning, sql server table partition, table partition, hash partitioning, composite partitioning, sql server partitioning, sql server table partitioning, partition table, types of partitions, what is partition, advantages of partition, partition index, sql tutorials for beginners, sql expert, sql expert tutorials, database, oracle, table, online training,insert into oracle,oracle insert into multiple rows,create table oracle,oracle 12c alter table add identity column,oracle create table default value sysdate,collections in oracle pl sql with examples,Oracle 12c, database, oracle database (software), sql, sql developer, sql tutorials, how to create database using dbca, how to create database in oracle,oracle cloud, database 12c, dba genesis,database services, database, create, 11g, dba, db, beginner, Please Subscribe My Channel
11-How to create an index for a column in a table in a SQL Server database
 
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Original high quality video: http://www.dotnetcodecentral.com/Post/130/microsoft-sql-server-quick-learn-how-to/How-to-create-an-index-for-a-column-in-a-SQL-Server-table All high quality videos on SQL Server (FREE to download): http://www.dotnetcodecentral.com/Technology/microsoft-sql-server-quick-learn-how-to Demonstrates the following (using SQL Server Management Studio): -Open a table in design mode (to modify table structure) -Add an index to a column in a table
Views: 17863 Jagadish Pulakhandam
Oracle 12c new feature Identity column
 
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Oracle 12c new feature Identity column oracle identity column identity columns in oracle 12c
Views: 366 Siva Academy
Oracle Training Index Creation-NewayITSolutions
 
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Oracle Training Index Creation-NewayITSolutions Learn how easy it is to make $100k and above by becoming an Oracle Database Administrator. Website: https://newayitsolutions.com Subscribe: https://newayitsolutions.com/page Enroll: https://newayitsolutions.com/enroll Youtube: newayitsolutions ------------------------------------------------------------------------------------------------------------------------------------------------------------- Follow on Facebook: https://www.facebook.com/newayitsolutions/ Follow on Twitter: https://twitter.com/Theoracledbaguy Follow on Instagram: https://www.instagram.com/oracledbatrainer/ Financing Available: https://newayitsolutions.com/loan-application School Locations: Atlanta, Maryland, Virginia ------------------------------------------------------------------------------------------------------------------------------------------------------------- Office Contact: 1-866-569-0205 Mobile Contact: 240-244-9935
How to create Virtual Columns in Oracle Database
 
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How to create Virtual Columns in Oracle Database 12c When queried, virtual columns appear to be normal table columns, but their values are derived rather than being stored on disc. The syntax for defining a virtual column is listed below. column_name [datatype] [GENERATED ALWAYS] AS (expression) [VIRTUAL] If the datatype is omitted, it is determined based on the result of the expression. The GENERATED ALWAYS and VIRTUAL keywords are provided for clarity only. The script below creates and populates an employees table with two levels of commission. It includes two virtual columns to display the commission-based salary. The first uses the most abbreviated syntax while the second uses the most verbose form. CREATE TABLE employees ( id NUMBER, first_name VARCHAR2(10), last_name VARCHAR2(10), salary NUMBER(9,2), comm1 NUMBER(3), comm2 NUMBER(3), salary1 AS (ROUND(salary*(1+comm1/100),2)), salary2 NUMBER GENERATED ALWAYS AS (ROUND(salary*(1+comm2/100),2)) VIRTUAL, CONSTRAINT employees_pk PRIMARY KEY (id) ); INSERT INTO employees (id, first_name, last_name, salary, comm1, comm2) VALUES (1, 'JOHN', 'DOE', 100, 5, 10); INSERT INTO employees (id, first_name, last_name, salary, comm1, comm2) VALUES (2, 'JAYNE', 'DOE', 200, 10, 20); COMMIT; Querying the table shows the inserted data plus the derived commission-based salaries. SELECT * FROM employees; ID FIRST_NAME LAST_NAME SALARY COMM1 COMM2 SALARY1 SALARY2 ---------- ---------- ---------- ---------- ---------- ---------- ---------- ---------- 1 JOHN DOE 100 5 10 105 110 2 JAYNE DOE 200 10 20 220 240 2 rows selected. SQL The expression used to generate the virtual column is listed in the DATA_DEFAULT column of the [DBA|ALL|USER]_TAB_COLUMNS views. COLUMN data_default FORMAT A50 SELECT column_name, data_default FROM user_tab_columns WHERE table_name = 'EMPLOYEES'; COLUMN_NAME DATA_DEFAULT ------------------------------ -------------------------------------------------- ID FIRST_NAME LAST_NAME SALARY COMM1 COMM2 SALARY1 ROUND("SALARY"*(1+"COMM1"/100),2) SALARY2 ROUND("SALARY"*(1+"COMM2"/100),2) 8 rows selected. SQL Notes and restrictions on virtual columns include: 1)Indexes defined against virtual columns are equivalent to function-based indexes. 2)Virtual columns can be referenced in the WHERE clause of updates and deletes, but they cannot be manipulated by DML. 3)Tables containing virtual columns can still be eligible for result caching. 4)Functions in expressions must be deterministic at the time of table creation, but can subsequently be recompiled and made non-deterministic without invalidating the virtual column. In such cases the following steps must be taken after the function is recompiled: a)Constraint on the virtual column must be disabled and re-enabled. b)Indexes on the virtual column must be rebuilt. c)Materialized views that access the virtual column must be fully refreshed. d)The result cache must be flushed if cached queries have accessed the virtual column. e)Table statistics must be regathered. 5)Virtual columns are not supported for index-organized, external, object, cluster, or temporary tables. 6)The expression used in the virtual column definition has the following restrictions: a.It cannot refer to another virtual column by name. b.It can only refer to columns defined in the same table. c.If it refers to a deterministic user-defined function, it cannot be used as a partitioning key column. e.The output of the expression must be a scalar value. It cannot return an Oracle supplied datatype, a user-defined type, or LOB or LONG RAW.
Views: 570 OracleDBA
Oracle Database 12c: Partitioning Improvements with Tom Kyte
 
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Tom Kyte introduces the new partitioning improvements in Oracle Database 12c, followed by a demo of global index maintenance. For more information: "Asynchronous Global Index Maintenance for Dropping and Truncating Partitions" http://www.oracle.com/pls/topic/lookup?ctx=db121&id=VLDBG14107 "Changes for Very Large Databases and Partitioning in Oracle Database 12c Release 1" http://www.oracle.com/pls/topic/lookup?ctx=db121&id=VLDBG14100 "ALTER INDEX COALESCE Clause" http://www.oracle.com/pls/topic/lookup?ctx=db121&id=SQLRF52782 "DBMS_PART.CLEANUP_GIDX Procedure" http://www.oracle.com/pls/topic/lookup?ctx=db121&id=ARPLS74409
Views: 14158 OracleDBVision
Oracle SQL Tutorials 20 ll Querying data   Part 3   Column Aliases
 
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USING SQL COMMAND Types of SQL Commands The following sections discuss the basic categories of commands used in SQL to perform various functions. These functions include building database objects, manipulating objects, populating database tables with data, updating existing data in tables, deleting data, performing database queries, controlling database access, and overall database administration. The main categories are DDL (Data Definition Language) DML (Data Manipulation Language) DQL (Data Query Language) DCL (Data Control Language) Data administration commands Transactional control commands Defining Database Structures Data Definition Language, DDL, is the part of SQL that allows a database user to create and restructure database objects, such as the creation or the deletion of a table. Some of the most fundamental DDL commands discussed during following hours include the following: CREATE TABLE ALTER TABLE DROP TABLE CREATE INDEX ALTER INDEX DROP INDEX CREATE VIEW DROP VIEW Manipulating Data Data Manipulation Language, DML, is the part of SQL used to manipulate data within objects of a relational database. There are three basic DML commands: INSERT UPDATE DELETE Selecting Data Though comprised of only one command, Data Query Language (DQL) is the most concentrated focus of SQL for modern relational database users. The base command is as follows: SELECT This command, accompanied by many options and clauses, is used to compose queries against a relational database. Queries, from simple to complex, from vague to specific, can be easily created. The SELECT command is discussed in exhilarating detail during Hours 7 through 16. A query is an inquiry to the database for information. A query is usually issued to the database through an application interface or via a command line prompt. Data Control Language Data control commands in SQL allow you to control access to data within the database. These DCL commands are normally used to create objects related to user access and also control the distribution of privileges among users. Some data control commands are as follows: ALTER PASSWORD GRANT REVOKE CREATE SYNONYM You will find that these commands are often grouped with other commands and may appear in a number of different lessons throughout this book. Data Administration Commands Data administration commands allow the user to perform audits and perform analyses on operations within the database. They can also be used to help analyze system performance. Two general data administration commands are as follows: START AUDIT STOP AUDIT Do not get data administration confused with database administration. Database administration is the overall administration of a database, which envelops the use of all levels of commands. Database administration is much more specific to each SQL implementation than are those core commands of the SQL language. Transactional Control Commands In addition to the previously introduced categories of commands, there are commands that allow the user to manage database transactions. COMMIT Saves database transactions ROLLBACK Undoes database transactions SAVEPOINT Creates points within groups of transactions in which to ROLLBACK SET TRANSACTION Places a name on a transaction Transactional commands are discussed extensively during Hour 6, "Managing Database Transactions." sql interview questions,sql interview questions and answers,interview questions for freshers,SQL,sql tutorial BEGINNERS,oracle,pl sql,pl/sql,mysql,oracle interview,google interview question,trigger in oracle,dbms,rdbms, oracle tutorial,pl sql basics,pl sql tutorials, pl sql example,sql,sql server ,query,sql query,questions,interview questions,coding interview,sql coding, code , database interview questions and answers,interview questions sql, interview questions,sql server,sql interview,interview sql,interview question sql join ,inner join, group by,select sql,interview questions ,sql basic, PL SQL Programs,PL SQL,PL SQL block,PL SQL Function,PL SQL Package,PL SQL Package body,PL SQL Procedure ,PL SQL Trigger,PL SQLType,PL SQL Type body,CREATE OR REPLACE PROCEDURE,database interview questions and answers,interview questions sql, interview questions,sql server,Procedural Language,interview sql,interview question sql join ,inner join, group by,select sql,interview questions ,sql basic,pl sql variable,oraclecoach,claire rajan, PL SQL,PL SQL block,PL SQL Function,PL SQL Package,PL SQL Package body,PL SQL Procedure,PL SQL Trigger,PL SQLType,PL SQL
14. Pseudo Columns
 
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In this video you will learn about Pseudo columns used in Oracle engine. This is one of confusing topic for beginners, if you are one you should quickly watch it. You will remember it always after watching. For Support =========== Email: [email protected] Contact Form: http://www.learninhindi.com/home/contact Our Social Media ================ Facebook: https://www.facebook.com/LearnInHindi Twitter: https://twitter.com/LearnInHindi For Training & Videos ===================== For more videos and articles visit: http://www.learninhindi.com Free Java Programming In Hindi Course ===================================== https://www.youtube.com/playlist?list=PLOZ3jentlCDAwwhMyoLISrxkXTADGp7PH Free Oracle PL/SQL Programming In Hindi Course ============================================== https://www.youtube.com/playlist?list=PLB5DA82419C2D99B6 Free C Programming In Hindi Course ================================== https://www.youtube.com/playlist?list=PLOZ3jentlCDAxKpBLMWogxSdy6BZcsAJq Trips & Tricks Channel ====================== https://www.youtube.com/channel/UCGmLfkuCo-3lHHJXRJ9HUMw Programming in Hindi Channel ============================ https://www.youtube.com/channel/UCudElIDgwNrybeAvXIy1HZQ
Views: 41764 ITORIAN
SQL Tutorial - 13: Inserting Data Into a Table From Another Table
 
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In this tutorial we'll learn to use the INSERT Query to copy data from one table into another.
Views: 270767 The Bad Tutorials
Sql Server Tutorial:Create ,Alter and Drop a database Part-2
 
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How To Create,Alter, Drop A Database In Sql Server Create, Alter And Drop - Database And Table - Sqlrelease Drop Database (Transact-Sql) - Msdn - Microsoft Create, Alter, And Drop Filetables - Msdn - Microsoft Sql Alter Table Statement - W3schools Sql Create Index Statement - W3schools Sql Create/Alter/Drop Schema - W3resource Sql Create/Alter Database - W3resource How To Force Drop Database In Sql Server 2008 - Database ... How To Create, Alter, Rename, And Drop Tables In Sql ... Dropping Creating And Altering Databases In Microsoft Sql Server ... Sql Add Column Sql Update Sql Drop Table Sql Insert Into Sql Create Table String Or Binary Data Would Be Truncated. Sql Server: Alter Table Statement - Techonthenet Dropping An Offline Database In Sql Server - Brent Ozar Unlimited® Auditing Ddl (Create, Alter, Drop) Commands In Sql Server 2005 Ddl Triggers For Auding Database Objects In Sql Server - Sql Book Selecting, Creating, Dropping, And Altering Databases | Mysql Sql ... Sql Drop Or Delete Database - Tutorialspoint Sql Server - Alter Database Dbname Set Single_User ... How I Completely Remove A Sql Server Database - Blog Pieter ... Mysql 5.7 Reference Manual :: 7.2.1 Privileges Provided By Mysql Drop Triggers In Sql | Sql Add Column Sql Update Sql Drop Table Sql Insert Into Sql Create Table String Or Binary Data Would Be Truncated. How To Create,Alter, Drop A Database In Sql Server
How to create Foreign Key Constraint on Multiple Columns in SQL Server - SQL Server Tutorial Part 67
 
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SQL Server / TSQL Tutorial Scenario: You are working as SQL Server developer, you need to create a table dbo.Customer with composite primary key by using columns FName and SSN. One you are done with creating primary key in dbo.Customer table, you need to create second table dbo.Orders and create foreign key constraint by using Primary Key columns. Link to scripts used in SQL Server / TSQL Tutorial Video http://www.techbrothersit.com/2016/04/how-to-create-foreign-key-constraint-on.html Check out our website for Different SQL Server, MSBI tutorials and interview questions such as SQL Server Reporting Services(SSRS) Tutorial SQL Server Integration Services(SSIS) Tutorial SQL Server DBA Tutorial SQL Server / TSQL Tutorial ( Beginner to Advance) http://www.techbrothersit.com/
Views: 5617 TechBrothersIT
03 - Curso de Oracle 10g - Alter Table Add
 
09:28
Curso Oracle SQL Essentials http://bit.ly/1N3upVn Curso Oracle SQL Expert - Certificação 1Z0-047 http://bit.ly/1G4rKWG Curso Oracle Aprendendo SQL - Preparatório exames 1Z0-051/1Z0-061 http://bit.ly/1eqDlsr Neste Curso de Oracle 10g será demonstrado todo passo a passo desde a istalação até administração e programação em PLSql. No Curso de Oracle 10g você será direcionado passo a passo durante o aprendizado com ótima qualidade do conteúdo disponibilizado. Este curso é oferecido gratuitamente aqui porém caso tenha interesse em se aprofundar e aprender o oracle a fundo praparando para certificação acesse os links acima. Tags: oracle cursos gratuitos curso de oracle banco de dados
Views: 4876 Cursos Interativos
Oracle SQL Tutorials 40 llJoining Tables   SQL 1999 syntax Hands on Part 1
 
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CREATE TABLE command in sql/oracle,INSERT command in sql/oracle UPDATE,ALTER PASSWORD command in sql, GRANT command, REVOKE command i, CREATE SYNONYM command in sql/oracle, DELETE command in sql/oracle, ALTER TABLE command in sql/oracle, DROP TABLE command in sql/oracle, CREATE INDEX command in sql/oracle, ALTER INDEX command in sql/oracle, DROP INDEX command in sql/oracle, CREATE VIEW command in sql/oracle, DROP VIEW command in sql/oracle, USING SQL COMMAND Types of SQL Commands The following sections discuss the basic categories of commands used in SQL to perform various functions. These functions include building database objects, manipulating objects, populating database tables with data, updating existing data in tables, deleting data, performing database queries, controlling database access, and overall database administration. The main categories are DDL (Data Definition Language) DML (Data Manipulation Language) DQL (Data Query Language) DCL (Data Control Language) Data administration commands Transactional control commands Defining Database Structures Data Definition Language, DDL, is the part of SQL that allows a database user to create and restructure database objects, such as the creation or the deletion of a table. Some of the most fundamental DDL commands discussed during following hours include the following: CREATE TABLE ALTER TABLE DROP TABLE CREATE INDEX ALTER INDEX DROP INDEX CREATE VIEW DROP VIEW Manipulating Data Data Manipulation Language, DML, is the part of SQL used to manipulate data within objects of a relational database. There are three basic DML commands: INSERT UPDATE DELETE Selecting Data Though comprised of only one command, Data Query Language (DQL) is the most concentrated focus of SQL for modern relational database users. The base command is as follows: SELECT This command, accompanied by many options and clauses, is used to compose queries against a relational database. Queries, from simple to complex, from vague to specific, can be easily created. The SELECT command is discussed in exhilarating detail during Hours 7 through 16. A query is an inquiry to the database for information. A query is usually issued to the database through an application interface or via a command line prompt. Data Control Language Data control commands in SQL allow you to control access to data within the database. These DCL commands are normally used to create objects related to user access and also control the distribution of privileges among users. Some data control commands are as follows: ALTER PASSWORD GRANT REVOKE CREATE SYNONYM You will find that these commands are often grouped with other commands and may appear in a number of different lessons throughout this book. Data Administration Commands Data administration commands allow the user to perform audits and perform analyses on operations within the database. They can also be used to help analyze system performance. Two general data administration commands are as follows: START AUDIT STOP AUDIT Do not get data administration confused with database administration. Database administration is the overall administration of a database, which envelops the use of all levels of commands. Database administration is much more specific to each SQL implementation than are those core commands of the SQL language. Transactional Control Commands In addition to the previously introduced categories of commands, there are commands that allow the user to manage database transactions. COMMIT Saves database transactions ROLLBACK Undoes database transactions SAVEPOINT Creates points within groups of transactions in which to ROLLBACK SET TRANSACTION Places a name on a transaction Transactional commands are discussed extensively during Hour 6, "Managing Database Transactions."
How to Detect Soft Corruption in Oracle 12c Database
 
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Detection of Soft Corruption in 12c: To use the scripts below replace : , ",# and $ by proper bracket Lets Create a tablespace and small table. SQL: create tablespace DEMO1 datafile '/u02/tstdb1/TSTDB1/datafile/demo01.dbf' size 50M SQL: create table objects tablespace DEMO1 as select * from dba_objects; SQL: alter table objects add constraint pk_obj primary key #object_id$; SQL: create index idx_obj_name on objects#object_name$ tablespace demo1; Backup tablespace. RMAN: backup tablespace DEMO1; We need to put the DB in archivelog first Rebuild index with NOLOGGING option to simulate soft corruption later. RMAN: alter index idx_obj_name rebuild nologging; Confirm that we have datafiles that require backup because they have been affected with NOLOGGING operation. RMAN: report unrecoverable; Simulate corruption. RMAN: alter database datafile 5 offline; RMAN: restore datafile 5; RMAN: recover datafile 5; RMAN: alter database datafile 5 online; Query table with corrupted index and notice error. SQL: select count#*$ from objects where object_name like 'A%'; Let’s perform validation of datafile to check block corruption. RMAN: backup validate check logical datafile 5; Notice that we have 457 blocks marked corrupt but v$database_block_corruption view is empty. SQL: select count#*$ from v$database_block_corruption; Let’s query v$nonlogged_block view. set lines 200 set pages 999 select file#, block#, blocks,object#,reason from v$nonlogged_block; Will RMAN detect that we have corrupted blocks? RMAN: backup datafile 5; RMAN backup won’t fail due to NOLOGGING corrupt blocks and our backup will contain soft corrupted blocks. Let’s Identify corrupt segments using v$nonlogged_block view. set lines 2000 set pages 9999 col owner for a20 col partition_name for a10 col segment_name for a20 SELECT e.owner, e.segment_type, e.segment_name, e.partition_name, c.file# , greatest#e.block_id, c.block#$ corr_start_block# , least#e.block_id+e.blocks-1, c.block#+c.blocks-1$ corr_end_block# , least#e.block_id+e.blocks-1, c.block#+c.blocks-1$ - greatest#e.block_id, c.block#$ + 1 blocks_corrupted FROM dba_extents e, V$NONLOGGED_BLOCK c WHERE e.file_id = c.file# AND e.block_id "= c.block# + c.blocks - 1 AND e.block_id + e.blocks - 1 := c.block# UNION SELECT s.owner, s.segment_type, s.segment_name, s.partition_name, c.file# , header_block corr_start_block# , header_block corr_end_block# , 1 blocks_corrupted FROM dba_segments s, V$NONLOGGED_BLOCK c WHERE s.header_file = c.file# AND s.header_block between c.block# and c.block# + c.blocks - 1 UNION SELECT null owner, null segment_type, null segment_name, null partition_name, c.file# , greatest#f.block_id, c.block#$ corr_start_block# , least#f.block_id+f.blocks-1, c.block#+c.blocks-1$ corr_end_block# , least#f.block_id+f.blocks-1, c.block#+c.blocks-1$ - greatest#f.block_id, c.block#$ + 1 blocks_corrupted FROM dba_free_space f, V$NONLOGGED_BLOCK c WHERE f.file_id = c.file# AND f.block_id "= c.block# + c.blocks - 1 AND f.block_id + f.blocks - 1 := c.block# order by file#, corr_start_block# / This is the best outcome to get if you notice corruption errors. All errors are related to index corruption so we could fix this problem rebuilding index. alter index idx_obj_name rebuild; Simply issuing "alter index rebuild" command won't work. We should mark index unusable to drop segment before rebuilding it or just rebuild index with online option. It is better choice to mark index unusable because you don't need additional space then, but I will simply rebuild index with online option and see what will happen. SQL: alter index idx_obj_name rebuild online; Index altered. SQL: select count#*$ from objects where object_name like 'A%'; No errors... but, let's validate datafile for corruption. RMAN: backup validate check logical datafile 5; Notice "Marked Corrupt" column. Hm... 457 like before. Don't worry, this is not new corruption. These are FREE blocks which will be reused and Oracle will automatically re-format those blocks. Query the v$nonlogged_block view again as given above. We could force re-formatting creating dummy table and inserting data to dummy table. Check Doc ID 336133.1. create table s # n number, c varchar2#4000$ $ nologging tablespace DEMO1; SQL: BEGIN FOR i IN 1..1000000 LOOP INSERT /*+ APPEND */ INTO sys.s select i, lpad#'REFORMAT',3092, 'R'$ from dual; commit ; END LOOP; END; / SQL: drop table sys.s purge; Notice that we don't have corrupted blocks any more. RMAN: backup validate check logical datafile 5;
Views: 222 OracleDBA
SQL Server 26 - PRIMARY KEY, NOT NULL, UNIQUE
 
03:36
In the last video we created our first table, but I want to give SQL Server some extra information so the database knows more about each of the columns. The first thing is to establish the primary key. To do this all we do is add PRIMARY KEY after the column we want to be the primary key. Simple enough. When we add a constraint right after the column like this, it is often called a column attribute. CREATE TABLE Animals( ID INT PRIMARY KEY, Name VARCHAR(50), Species VARCHAR(50) ); Additionally, if you are using an ID column, it is best to have it labeled as the IDENTITY column. That way, SQL Server will automatically increment the number. CREATE TABLE Animals( ID INT PRIMARY KEY IDENTITY, Name VARCHAR(50), Species VARCHAR(50) ); The other attributes we've discussed in this series are NOT NULL and UNIQUE. We can make the name NOT NULL and the species NOT NULL. We don't have a good column for UNIQUE, so let's add one: CREATE TABLE Animals( ID INT PRIMARY KEY IDENTITY, Name VARCHAR(50) NOT NULL, Species VARCHAR(50) NOT NULL, ContactEmail VARCHAR(50) NOT NULL UNIUQE ); You can see that it is very easy to add multiple column attributes to a column. Just separate them by spaces. The order does not matter. Also, when you say primary key the column is automatically NOT NULL and UNIQUE. There are other attributes you can use including DEFAULT, FOREIGN KEY, and SPARSE. DEFAULT will give a value for a column if you do not put anything in yourself. Foreign keys are used to reference other columns. SPARSE is an attribute we haven't discussed. You can use SPARSE if most of the rows are going to have a NULL for a column and it saves storage space, but we will worry about that in another video. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Support me! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://bit.ly/JoinCCNewsletter Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://twitter.com/calebCurry Amazing Web Hosting - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 6269 Caleb Curry
PIVOT Tutorial - generating dynamic column with PIVOT Interview Question SQL
 
14:14
In this lecture you will learn about PIVOT operator and using it to generate dynamic columns.PIVOT is very use full operator to convert values into columns. PIVOT: •Convert your output from (values)vertical order to horizontal(making columns) one Topic to cover: •PIVOT example •PIVOT syntax •Interview Question •PIVOT on northwind •Dynamic PIVOT query http://www.techsapphire.in/index/pivot_sql_lesson_with_generating_dynamic_columns_with_pivot/0-158
Views: 32235 techsapphire