UPDATE Query

UPDATE query is used to update existing records.

Syntax

UPDATE table_name

SET col1=val1, col2=val2….colN=valN

[WHERE condition];

mysql> SELECT * FROM employee;
+----+---------+------+-------------+---------------------+------------+
| id | name    | age  | salary      | mailId              | city       |
+----+---------+------+-------------+---------------------+------------+
|  1 | Hari    |   28 |  12345.6700 | hari@hari.com       | Bangalore  |
|  2 | Sandesh |   31 |  98345.0000 | sandesh@sandesh.com | Trivendram |
|  3 | Phalgum |   33 | 119345.6700 | phalgun@hari.com    | Hyderabad  |
|  4 | Manju   |   36 |  87666.8700 | manju@sandesh.com   | Bangalore  |
|  5 | Rakesh  |   26 |  38000.0000 | rakesh@hari.com     | Bangalore  |
|  6 | Sankalp |   38 |  87645.6700 | sankalp@sankalp.com | Chenai     |
|  7 | Vadiraj |   40 |  12345.6700 | vadi@hari.com       | Bangalore  |
|  8 | Prasob  |   37 |  12345.6700 | prasob@sandesh.com  | Trivendram |
|  9 | Kesav   | NULL | 123457.8900 | NULL                | NULL       |
+----+---------+------+-------------+---------------------+------------+
9 rows in set (0.00 sec)

a. Change the age of an employee with id 1 to 23.

mysql> UPDATE employee SET age=23 WHERE id = 1;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0  

mysql> SELECT * FROM employee;
+----+---------+------+-------------+---------------------+------------+
| id | name    | age  | salary      | mailId              | city       |
+----+---------+------+-------------+---------------------+------------+
|  1 | Hari    |   23 |  12345.6700 | hari@hari.com       | Bangalore  |
|  2 | Sandesh |   31 |  98345.0000 | sandesh@sandesh.com | Trivendram |
|  3 | Phalgum |   33 | 119345.6700 | phalgun@hari.com    | Hyderabad  |
|  4 | Manju   |   36 |  87666.8700 | manju@sandesh.com   | Bangalore  |
|  5 | Rakesh  |   26 |  38000.0000 | rakesh@hari.com     | Bangalore  |
|  6 | Sankalp |   38 |  87645.6700 | sankalp@sankalp.com | Chenai     |
|  7 | Vadiraj |   40 |  12345.6700 | vadi@hari.com       | Bangalore  |
|  8 | Prasob  |   37 |  12345.6700 | prasob@sandesh.com  | Trivendram |
|  9 | Kesav   | NULL | 123457.8900 | NULL                | NULL       |
+----+---------+------+-------------+---------------------+------------+
9 rows in set (0.00 sec)

b. Increment salaries of employees by 10%.

mysql> UPDATE employee SET salary=salary*1.1;
Query OK, 9 rows affected (0.00 sec)
Rows matched: 9  Changed: 9  Warnings: 0

mysql> SELECT * FROM employee;
+----+---------+------+-------------+---------------------+------------+
| id | name    | age  | salary      | mailId              | city       |
+----+---------+------+-------------+---------------------+------------+
|  1 | Hari    |   23 |  13580.2370 | hari@hari.com       | Bangalore  |
|  2 | Sandesh |   31 | 108179.5000 | sandesh@sandesh.com | Trivendram |
|  3 | Phalgum |   33 | 131280.2370 | phalgun@hari.com    | Hyderabad  |
|  4 | Manju   |   36 |  96433.5570 | manju@sandesh.com   | Bangalore  |
|  5 | Rakesh  |   26 |  41800.0000 | rakesh@hari.com     | Bangalore  |
|  6 | Sankalp |   38 |  96410.2370 | sankalp@sankalp.com | Chenai     |
|  7 | Vadiraj |   40 |  13580.2370 | vadi@hari.com       | Bangalore  |
|  8 | Prasob  |   37 |  13580.2370 | prasob@sandesh.com  | Trivendram |
|  9 | Kesav   | NULL | 135803.6790 | NULL                | NULL       |
+----+---------+------+-------------+---------------------+------------+
9 rows in set (0.00 sec)

If you don’t specify any condition, then it reflects entire table.

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