Relational databases have three types of languages: (Data Description Language) DDL ), (Data manipulation language DML ) And (Data Control Language DCL ), And SQL Yes (Set DDL , DML , DCL Standard relational database language.
DDL is Data Definition Language statements. Some examples:
- Create-to create objects in the database
- Alter-alters the structure of the database
- Drop-delete objects from the database
- Truncate-Remove all records from a table, including all spaces allocated for the records are removed
- Comment-add comments to the data dictionary
- Grant-gives user's access privileges to database
- Revoke-withdraw access privileges given with the grant command
DML is data manipulation language statements. Some examples:
- Select-retrieve data from the Database
- Insert-insert data into a table
- Update-updates existing data within a table
- Delete-deletes all records from a table, the space for the records remain
- Call-call a PL/SQL or Java Subprogram
- Explain plan-explain access path to data
- Lock table-control concurrency
DCL is Data Control Language statements. Some examples:
- Commit-save work done
- Savepoint-identify a point in a transaction to which you can later roll back
- Rollback-Restore database to original since the last commit
- SET transaction-change transaction options like what rollback segment to use
