On Friday 08 August 2014, Jason Penton wrote:
I have noticed that in some instances if you update a row in mysql via the mysql_db module and the actual row data does not change - affected_rows will return 0. This is the default behaviour for the mysql API as per - http://dev.mysql.com/doc/refman/5.0/en/mysql-real-connect.html
There is a flag (CLIENT_FOUND_ROWS) that can be used in the mysql_real_connect function that will cause affected_rows to return the number of rows that were "matched" - ie in the WHERE clause, as opposed to whether or not any data was changed.
If we don't it could be a problem for modules like usrloc where an update is done and if no row are "affected" and new row is added which would cause a duplicate.
If that happens, the table definition is wrong. It should have (a) unique key(s) to prevent double records. We'd better fix that.