If you modify multiple records, the TIMESTAMP values in all of them will be updated:

     
mysql>
mysql>
mysql> CREATE TABLE tsdemo1
    -> (
    ->     t TIMESTAMP,
    ->     val INT
    -> );
Query OK, 0 rows affected (0.01 sec)

mysql>
mysql> INSERT INTO tsdemo1 (t,val) VALUES(NULL,5);
Query OK, 1 row affected (0.00 sec)

mysql> INSERT INTO tsdemo1 (val) VALUES(10);
Query OK, 1 row affected (0.00 sec)

mysql>
mysql> SELECT * FROM tsdemo1;
+---------------------+------+
| t                   | val  |
+---------------------+------+
| 2011-10-03 13:05:52 |    5 |
| 2011-10-03 13:05:52 |   10 |
+---------------------+------+
2 rows in set (0.00 sec)

mysql>
mysql> UPDATE tsdemo1 SET val = 6 WHERE val = 5;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> SELECT * FROM tsdemo1;
+---------------------+------+
| t                   | val  |
+---------------------+------+
| 2011-10-03 13:05:52 |    6 |
| 2011-10-03 13:05:52 |   10 |
+---------------------+------+
2 rows in set (0.00 sec)

mysql>
mysql>
mysql> UPDATE tsdemo1 SET val = val + 1;
Query OK, 2 rows affected (0.00 sec)
Rows matched: 2  Changed: 2  Warnings: 0

mysql> SELECT * FROM tsdemo1;
+---------------------+------+
| t                   | val  |
+---------------------+------+
| 2011-10-03 13:05:52 |    7 |
| 2011-10-03 13:05:52 |   11 |
+---------------------+------+
2 rows in set (0.00 sec)

mysql>
mysql> drop table tsdemo1;
Query OK, 0 rows affected (0.00 sec)

Related examples in the same category

1.	The TIMESTAMP column type
2.	Displaying TIMESTAMP Values in Readable Form
3.	Table with TIMESTAMP data type
4.	Add Microsecond to time
5.	Records created from 1 PM to 4 PM:
6.	Records modified within the last 12 hours:

If you modify multiple records, the TIMESTAMP values in all of them will be updated: : TIMESTAMP « Date Time « SQL / MySQL

Related examples in the same category