Question

In my LAMP application (using CodeIgniter), I have a call to $this->db->update… that generates a SQL like the following:

UPDATE `MyTable` SET `MyProcess` = 5 WHERE `Id` = 1

The problem is that this seems to work intermittently — and I currently have no idea what might be wrong. Is there anything about MySQL I need to know about when trying to update? I’m adding & updating records a lot (but probably no more than one query every 5 seconds). When I run the query in phpMyAdmin, it works fine.

Answer 1

This is an addition to Mark’s answer. mysql_affected_rows also returns 0 if you try to update a record but the values in that record do not change.

For example; current values in MyTable:

+----+-----------+
| ID | MyProcess |
+----+-----------+
| 1  | 5         |
+----+-----------+

Then when you run your query:

UPDATE `MyTable` SET `MyProcess` = 5 WHERE `Id` = 1

mysql_affected_rows will return 0

Could this be what is happening in your case?