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1.7 alteR taBle

            In Structured Query Language, the ALTER TABLE statement allows you to add, modify, and delete columns from an existing
            table. This statement also allows database administrators to add and remove SQL constraints from existing tables.
            Syntax:

            ALTER TABLE table_name
            ADD column name datatype;
            Example:

            ALTER TABLE EmpLOyEE_DETAiLS
            ADD Emp_iD varchar(5);
            Output:
            +-----------------+-------------+------+-----+---------+-------+
            | Field           | Type        | Null | Key | Default | Extra |
            +-----------------+-------------+------+-----+---------+-------+
            | Emp_NAmE        | varchar(20) | yES  |     | NULL    |       |
            | Emp_DEpARTmENT  | varchar(20) | yES  |     | NULL    |       |
            | Emp_DESiGNATiON | varchar(20) | yES  |     | NULL    |       |
            | DATE_OF_BiRTH   | date        | yES  |     | NULL    |       |
            | ADDRESS         | varchar(20) | yES  |     | NULL    |       |
            | Emp_iD          | varchar(5)  | yES  |     | NULL    |       |
            +-----------------+-------------+------+-----+---------+-------+
            You can set a column as Primary Key with the following Command.

            ALTER TABLE Table_Name
            ADD pRimARy KEy (Column_Name);
            Example:

            ALTER TABLE EmpLOyEE_DETAiLS
            ADD pRimARy KEy (Emp_iD);
            Output:
            +-----------------+-------------+------+-----+---------+-------+
            | Field           | Type        | Null | Key | Default | Extra |
            +-----------------+-------------+------+-----+---------+-------+
            | Emp_NAmE        | varchar(20) | yES  |     | NULL    |       |
            | Emp_DEpARTmENT  | varchar(20) | yES  |     | NULL    |       |
            | Emp_DESiGNATiON | varchar(20) | yES  |     | NULL    |       |
            | DATE_OF_BiRTH   | date        | yES  |     | NULL    |       |
            | ADDRESS         | varchar(20) | yES  |     | NULL    |       |
            | Emp_iD          | varchar(5)  | NO   | pRi | NULL    |       |
            +-----------------+-------------+------+-----+---------+-------+
              1.8 upDate taBle

            UPDATE command is used to modify the existing records in a table.
            Syntax:

            UpDATE table_name
            SET column1 = value1, column2 = value2, ...
            WHERE condition;
            Example:
            UpDATE EmpLOyEE_DETAiLS
            SET EMP_ID = ′EMP05′ WHERE EMP_NAME = ′SOMNATH_PATRA′



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