When you talk with your database, you use a language that is understandable to the database component you access and specific to the vendor. There are multiple vendor-specific languages such as T-SQL, PL-SQL and SQL PL for Microsoft SQL Server, Oracle and IBM DB2 databases respectively. Although there are different vendor-specific implementations, general categorization of the database language, in terms of command types and operation type is as follows;
Do you know all of these languages? Can you describe what these acronym stand for and the purpose of them? Yes, that is the Brain Basher of the week.
Here is the explanation of each;
- DML - Data Manipulation Language - This language is used for manipulating data stored in tables. Operations such as inserting data, updating data are done with this language and SQL Server specific commands fall under this language are INSERT, UPDATE and DELETE.
- DDL - Data Definition Language - This helps us to define the structures used for holding data. This is used for operation like creating databases, creating tables and examples commands for this language are CREATE DATABASE, CREATE TABLE and CREATE VIEW.
- DCL - Data Control Language - This language is mainly used for controlling the access permission on objects created in the database and operations that can be performed on them. Operations such as granting permission to a user on a table for updating records, allowing a group to execute a stored procedure and commands such as GRANT SELECT, GRAN ALTER are examples for this.
- TCL - Transaction Control Language - Operations and commands related to transactions are come under this language. Starting a transaction with BEGIN TRAN and ending a transaction with either ROLLBACK TRAN or COMMIT TRAN are part of this language.
- DQL - Data Query Language - This represents SELECT SQL command that is used for retrieving data from the database.