Monday, July 19, 2021
Database Language
Types of Database Language
- Data definition language (DDL),
- Data manipulation language (DML),
- Data control language (DCL),
- Transaction control language (TCL),
Database Language
A DBMS has appropriate languages and interfaces to express database queries and updates.
Database languages can be used to read, store and update data in the database.
Types of Database Language
1. Data Definition Language
- DDL stands for Data Definition Language. It is used to define the database structure or pattern.
- It is used to create schema, tables, indexes, constraints etc in the database.
- Using DDL statements, you can create the skeleton of the database.
- Data Definition Language is used to store the information of Meta data such as number of tables and schemas, their names, indexes, columns in each table, constraints, etc.
Here are some tasks that come under DDL:
- Create: It is used to create objects in the database.
- Alter: It is used to change the structure of the database.
- Drop: It is used to delete objects from the database.
- Truncate: It is used to extract all the records from a table.
- Rename: It is used to rename an object
- Comments: It is used to comment on the data dictionary.
These commands are used to update the database schema, so they come under Data definition language.
2. Data Manipulation Language
DML stands for Data Manipulation Language. It is used to access and manipulate data in the database.
Here are some tasks that come under DML:
- Select: It is used to retrieve data from the database.
- Insert: It is used to insert data into the table.
- Select: It is used to retrieve data from the database.
- Insert: It is used to insert data into the table.
- Update: It is used to update the existing data within the table.
- Delete: It is used to delete all the records from a table.
- Merge: It performs UPSERT operations, which are insert or update operations.
- Call: It is used to call a structured query language or Java subprogram.
- Explain Plan: There is a parameter to explain the data in this
- Lock Table: It Controls Concurrency
3. Data Control Language
DCL stands for Data Control Language It is used to retrieve stored or saved data.
The execution of DCL is transactional. It also has rollback parameters.
(But in Oracle database, there is no rolling facility in the execution of data control language.)
Here are some tasks that come under DCL:
- Grant: It is used to grant user access privileges to a database.
- Revoke: It is used to revoke permission from the user.
There are the following operations which have the authorization of Revoke:
CONNECT, INSERT, USAGE, EXECUTE, DELETE, UPDATE and SELECT.
4. Transaction Control Language
TCL is used to drive changes made by DML statements. TCLs can be grouped in a logical transaction.
Here are some tasks that come under TCL:
- Commit: It is used to save the transaction on the database.
- Rollback: This is used to restore the original database since the last commit.