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Types of SQL Commands

            SQL commands are broadly classified into the given categories:
            •  Data Definition Language (DDL) commands
            •  Data Manipulation Language (DML) commands

            Data Definition Language (DDL)
            The SQL-DDL contains a set of commands that allows the users to make changes in the structure of the table like:
            •  Creating a new data definition using CREATE

            •  Adding, updating, removing the data definition using ALTER
            •  Deleting the data definition from the database using DROP.

            Syntax to create a new table in the database using SQL is as follows:
            CREATE TABLE <Table Name>
            (<Column Name1> <Data Type>,<Column Name2> <Data Type>,
            ... <Column Name n> <Data Type>);
            Example:

            CREATE TABLE student (RollNo Integer, Name VARCHAR(20), Fees integer, DOB Date,
            Marks integer);
            The syntax to display the structure of the table is as follows:

            DESCRIBE <Table Name> OR Desc <Table Name>
            For example,

            DESC STUDENT;
            OR
            DESCRIBE STUDENT;
            +--------+-------------+------+-----+---------+-------+
            | Field  | Type        | Null | Key | Default | Extra |
            +--------+-------------+------+-----+---------+-------+
            | RollNo | int         | YES  |     | NULL    |       |

            | Name   | varchar(20) | YES  |     | NULL    |       |
            | Fees   | int         | YES  |     | NULL    |       |
            | DOB    | date        | YES  |     | NULL    |       |
            | Marks  | int         | YES  |     | NULL    |       |
            +--------+-------------+------+-----+---------+-------+
            The syntax to add a new column(s) in the table is as follows:


            ALTER TABLE <Table Name>
            ADD (<Column Name1> <Data Type>,<Column Name2> <Data Type>,
            ... <Column Name n> <Data Type>);
            For examples,

            ALTER TABLE student ADD (ClassSec VARCHAR(30));








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