Description
Statements in SQL database includes the basic functionality of SQL keywords. SQL statements are divided into few types. The following are lists of SQL statements types:
| Type of SQL Statements | SQL Keywords |
|---|---|
| DDL | Create, Alter, Drop, Truncate |
| DML | Insert, Update, Delete |
| DCL | Grant, Revoke |
| TCL | Commit, Rollback, Save points |
Description
Data Definition Language(DDL) is utilized to characterize information in database server. DDL statements explains, how the pattern of data should be there in the database schema table and includes the following commands.
Create table articulation is utilized to make a table in the database server. And each table in the database should contain unique name and these tables are organised into rows and columns, where appropriate data or values should be inserted. And the column parameters specifies the name of the columns of the table and the datatypes parameters specifies the type of data that the column is holding that may vary from varchar, decimal, date and integers.
SQL Alter Table statement is used to add, modify, or delete a columns from the existing table. Alter Table command performs adding of column or modifying column size and is divided into two types.
Drop Table command can be performed on existing database. Indexes, tables, and databases can easily be erased/evacuated with the DROP statement. The following are the actions performed by drop command.
SQL is a non-procedural dialect. Client can compose SQL script to execute and SQL compiler consequently produces a method to get to database and convey the fancied output. SQL is a database coding, planned for the recuperation and organisation of data in social database. SQL Truncate command is utilized to erase all rows from the current table in the database."SQL Truncate Table" command shows how to truncate the rows in a table.
CreateAlterDropTruncate
- Add
- Modify
- Dropping a section from the table.
- Dropping a table from the database.
Description
Data manipulation language is utilized to manage data within the table.
By using SQL Insert command new record can be inserted in the existing database table. i.e, inserting field value like emp_id, emp_name and salary can be inserted.
By using SQL Update command, the column values can be updated i.e, changing the name of the employee and increasing/decreasing the salary. And the column parameters specifies the name of the columns of the table and the datatypes parameters specifies the type of data that the column is holding that may varies from varchar, decimal, date and integers.
By using SQL DELETE command rows can be deleted from an existing table taking into account the given condition.
InsertUpdateDelete
Description
To perform DML operations on a table permissions are required which are called "Privileges". And these privileges can be easily accessed by using Data Control Language.
GRANT is used to grant permissions to the clients. In the SQL database it offers both the server and client a great amount of control privileges. At the server side of the procedure, it incorporates the possibility for the server to control certain customer benefits over the SQL database away and reducing their connection permissions from the database or giving limited authorizations for a particular table.
The revoke command will cancel all the permissions from the user.
GrantRevoke
Description
A Transaction is a collection of SQL statement between specific client and server. And these transactions can be efficiently handled by using transaction control language.
If commit command is executed then all the work done in the last transaction will be made permanent in the server.
If roll-back command is performed then oracle server will cancel all the modifications of SQL statements in the last transactions.
If save points commands are performed, roll back operation will be performed on a part of transaction. The save points commands sets a name transaction save-point by the name of identifier. On the off chance present transaction has a save point with the similar name, then the old save point is deleted and a new one is assigned.
CommitRollbackSave points
Key Points
- Statements - Describe the SQL standard keyword in the database.
- Data Definition Language - Used to define data in database server.
- Data Manipulation Language - Used to manipulate data in the database server.
- Data Control Language - Perform operations on a table by giving permissions.
- Transaction Control Language - Will handle a transaction by using specific client and server.