Elena Stepanova added a comment - 2013-11-20 20:21 - edited Hi, What do :session_id, etc signify? Where do you execute the statement from? Could you please provide an example with real data, e.g. what you have in the table and what you are trying to update it to? In general, there is nothing strange about this error. Lets say you have this data in the table: MariaDB [test] > select * from user_session; ------- ---------- ------------ -------------+ php_id session_id session_data session_time ------- ---------- ------------ -------------+ a a a 2147483647 a b b 2147483647 ------- ---------- ------------ -------------+ 2 rows in set (0.00 sec) Then the following update will indeed cause the error: MariaDB [test] > update user_session set session_id = 'a' where php_id = 'a'; ERROR 1062 (23000): Duplicate entry 'a-a' for key 'PRIMARY' This is because you are updating several (two) rows at once, trying to modify them the way that their primary key becomes identical. But of course, it all depends on the data in the table and in the query.

Antoine Pous added a comment - 2013-11-21 11:45 Hi, thank you for your answer, i'm going wrong, this is not a bug. Sorry for the mistake :/