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Vincolo SQL per creare 2 clun non uguali tra loro

Questo è ora supportato a partire da MySQL 8.0.16.

Vedi https://dev.mysql. com/doc/refman/8.0/en/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.