I wouldn't recommend running it on an active table, but testing it in a throwaway table is reasonably easy. From the mysql commandline client (using mysql 4.0 ) 
mysql> create database pmtest;
Query OK, 1 row affected (0.09 sec)

mysql> use pmtest;
Database changed

mysql> create table t (id smallint, count smallint, time datetime);   
+                  Query OK, 0 rows affected (0.01 sec)

mysql> insert into t values (1,1,now());
Query OK, 1 row affected (0.00 sec)

mysql> insert into t values (2,1,now());
Query OK, 1 row affected (0.00 sec)

mysql> insert into t values (3,1,now());
Query OK, 1 row affected (0.00 sec)

mysql> update t set count=count+1, time=now() where id=2;
Query OK, 1 row affected (0.02 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> update t set count=count+1, time=now() where id=2;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> select * from t;
+------+-------+---------------------+
| id   | count | time                |
+------+-------+---------------------+
|    1 |     1 | 2007-02-22 19:26:39 |
|    2 |     3 | 2007-02-22 19:27:06 |
|    3 |     1 | 2007-02-22 19:26:45 |
+------+-------+---------------------+
3 rows in set (0.01 sec)

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In reply to Re^3: Updating a mysql row - testing with a throwaway table by imp
in thread Updating a mysql row by Anonymous Monk

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