SQL
•SQL (pronounced "ess-que-el") stands for Structured Query Language. SQL is used to communicate with a database. According to ANSI (American National Standards Institute), it is the standard language for relational database management systems. SQL statements are used to perform tasks such as update data on a database, or retrieve data from a database.
DDL
•Data Definition Language (DDL) statements are used to define the database structure or schema.
Commands:
1) CREATE - to create objects in the database
2) ALTER - alters the structure of the database
3) DROP - delete objects from the database
4) TRUNCATE - remove all records from a table, including all spaces allocated for the records are removed
5) RENAME - rename an object
DML
•Data Manipulation Language (DML) statements are used for managing data within schema objects.
Commands:
1) SELECT - retrieve data from the a database
2) INSERT - insert data into a table
3) UPDATE - updates existing data within a table
4) DELETE - deletes all records from a table, the space for the records remain
5) MERGE - UPSERT operation (insert or update)
DCL
•Data Control Language (DCL) statements.
Commands:
1) GRANT - gives user's access privileges to database
2) REVOKE - withdraw access privileges given with the GRANT command
TCL
•Transaction Control (TCL) statements are used to manage the changes made by DML statements. It allows statements to be grouped together into logical transactions.
Commands:
1) COMMIT - save work done
2) SAVEPOINT - identify a point in a transaction to which you can later roll back
3) ROLLBACK - restore database to original since the last COMMIT