Why Does My MySQL Trigger for Updating PTS Fail with 'Can't update table pos_table...' Error?

Troubleshooting Non-Functional MySQL Trigger for Updating PTS Column

A user faces a puzzling issue where a seemingly straightforward MySQL trigger fails to execute, prompting them to seek assistance. The trigger's purpose is to update a "PTS" column in the "pos_table" table based on changes in the "played_games" column.

Detailed inspection of the code reveals that the trigger should function correctly when the "played_games" column is modified. However, upon further troubleshooting, an error message is encountered: "Can't update table pos_table in stored function/trigger because it's already used by the statement which invoked this stored function/trigger."

This error suggests that a limitation of MySQL stored functions and triggers may be hindering the desired behavior. According to MySQL documentation, such functions and triggers cannot modify tables that are simultaneously used for reading or writing by the statement that invoked them.

A potential solution is to alter the trigger type to "BEFORE INSERT" and modify the values in the "NEW" variable.

Additionally, the user's intended calculation can be performed directly at display time rather than through a stored column, simplifying the code and eliminating the issue with the trigger.

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