MySQL 5.5 errno: 150 “Foreign key constraint is incorrectly formed”

Question

There are plenty of questions regarding this error but I can\'t seem to find any similar scenario to what I have.

My 1st table (users):

My 2nd table

Answer 1

• Verify that the datatypes match (except for PRIMARY KEY).
• Verify that both tables are ENGINE=InnoDB.

Even after that, error 150 can still occur. 3 ways around it:

• Disable FKs while creating the tables, then re-enable.
• CREATE TABLEs without FKs, then ALTER ... ADD ... FKs
• Be sure the do the CREATEs in just the right order.

A side note: In INT(2), the (2) is irrelevant. All INTs are 4 bytes.