Issuing an UPDATE statement that doesn't actually change the values in the val column doesn't update the TIMES : TimeStamp « Data Type « SQL / MySQL






  1. SQL / MySQL
  2. Data Type
  3. TimeStamp

Issuing an UPDATE statement that doesn't actually change the values in the val column doesn't update the TIMES

      
TAMP values.
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 + 0;
Query OK, 0 rows affected (0.00 sec)
Rows matched: 2  Changed: 0  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> drop table tsdemo1;
Query OK, 0 rows affected (0.00 sec)

mysql>








Related examples in the same category

1.TIMESTAMP as column type
2.timestamp type column default CURRENT_TIMESTAMP on update CURRENT_TIMESTAMP
3.Table definition includes a YEAR column and a TIMESTAMP
4.Order by timestamp value
5.dates and times in SQL commands must be given as character strings,
6.Recording a Row's Last Modification Time
7.Recording a Row's Creation Time
8.Performing Calculations with TIMESTAMP Values
9.Updates to tsdemo2 records that don't actually modify a column cause no change to TIMESTAMP values
10.Create a table in which timestamps can be stored.
11.The difference between the creation and modification times
12.microseconds component is removed.