gistfile1.txt

MariaDB [test]> create table t1 (id int unsigned not null auto_increment primary key);
Query OK, 0 rows affected (0.027 sec)

MariaDB [test]> create table t2 (id int unsigned not null auto_increment primary key, t1_id int unsigned not null, foreign key(t1_id) references t1(id));
Query OK, 0 rows affected (0.040 sec)

MariaDB [test]> insert into t2 (t1_id) values (1);
ERROR 1452 (23000): Cannot add or update a child row: a foreign key constraint fails (`test`.`t2`, CONSTRAINT `t2_ibfk_1` FOREIGN KEY (`t1_id`) REFERENCES `t1` (`id`))
MariaDB [test]> set foreign_key_checks=0;
Query OK, 0 rows affected (0.000 sec)

MariaDB [test]> insert into t2 (t1_id) values (1);
Query OK, 1 row affected (0.007 sec)

MariaDB [test]> set foreign_key_checks=1;
Query OK, 0 rows affected (0.000 sec)

MariaDB [test]>