What is SQL?
The Structured Query Language (SQL) is a standard programming language to access and manipulate databases. SQL allows the user to create, retrieve, alter, and transfer information among databases. It is a language designed for managing and accessing data in Relational Data Base Management System (RDBMS).
How to create a Database?
To create a database, type the following command in the prompt:
CREATE DATABASE database_name;
If you want to create a database containing information about the students then you can type,
CREATE DATABASE student;
NOTE: Any name can be given as database_name. In my example, I have taken it as student.
COMMANDS OF SQL
SQL commands are divided into 5 categories:
DDL – Data Definition Language
DML – Data Manipulation Language
DCL – Data Control Language
TCL -Transaction Control Language
DQL – Data Query Language
SQL commands under DDL are:
|CREATE||To create tables in the database.|
|ALTER||Alters the structure of the database.|
|DROP||Delete tables from database.|
|TRUNCATE||Remove all records from a table, also release the space occupied by those records.|
SQL commands under DML are:
|INSERT||Inserts data into a table.|
|UPDATE||Updates the existing data within a table.|
|DELETE||Delete all records from a table, but not the space occupied by them.|
SQL commands under DCL are:
|GRANT||Grants permission to one or more users to perform specific tasks.|
|REVOKE||Withdraws the access permission given by the GRANT statement.|
SQL commands under TCL are:
|COMMIT||Saves any transaction into the database permanently.|
|ROLL BACK||Restores the database to last COMMIT state.|
|SAVE POINT||Temporarily save a transaction so that you can ROLL BACK.|
SQL commands under DQL are:
|SELECT||It displays the records from the table.|
Now let us see how to create a table using SQL commands.
You can create a table by using the CREATE TABLE command.
CREATE TABLE table_name
( column name <data type> (size),
column name <data type> (size),……