ERROR 1452 (23000): Cannot add or update a child row: a foreign key constraint fails

Question

When I execute the following SQL command:

INSERT INTO test_usershosts (RID,userid,hid,Usr,Pass) 
VALUES (NULL,1,1,\"user\",\"pass\");

I\'m

Answer 1

In test_users guest's UserID is 1120 and in test_hosts hid = 30

you must change

INSERT INTO test_usershosts (RID,userid,hid,Usr,Pass) VALUES (NULL,1,1,"user","pass");

to:

INSERT INTO test_usershosts (RID,userid,hid,Usr,Pass) VALUES (NULL,1120,30,"user","pass");