SQL-begrænsning for at gøre 2 klumper ikke lig med hinanden

Dette er nu understøttet fra MySQL 8.0.16.

Se https://dev.mysql. com/doc/refman/8.0/da/create-table-check-constraints.html

mysql> create table id_parent_table (
    -> main_id bigint unsigned not null,
    -> parent_id bigint unsigned not null,
    -> constraint columns_cannot_equal check (main_id <> parent_id)
    -> );
Query OK, 0 rows affected (0.38 sec)

mysql> insert into id_parent_table (main_id, parent_id) values (1, 1);
ERROR 3819 (HY000): Check constraint 'columns_cannot_equal' is violated.