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FOR ADVANCED LEARNERS




              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));
              The syntax to delete a table (data as well as the structure) is as follows:
              DROP TABLE <Table Name>;
              For example,
              DROP TABLE Student;
              DML (Data Manipulation Language)
              DML is a language that enables users to access or manipulate data. By data manipulation, we mean:
              •  The retrieval of information stored in the table, using SELECT
              •  The insertion of new row with information into the table, using INSERT

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