MySQL. Can't create table errno 150

Question

I have to create a database with two tables in MySQL, but the script fails with errno 150 (foreign key problem). I double-checked the foreign key fields to be the same on bo

Answer 1

Yet another cause, although slightly similar to others: I was referring to a table that turned out to have the MyISAM engine, instead of InnoDB.

Answer 2

In my case, one table was using foreign key constraints on another table that didn't exist yet. This was happening due to a large makefile, so it wasn't as obvious as I would've expected.

Answer 3

In case somebody is still having problems with this, I tried all the solutions above (except for SET FOREIGN_KEY_CHECKS) and nothing worked. The problem was that when you reference the first table, some databases are case sensitive about the table names. I think this is weird since I never saw this before on MySQL, Oracle and now this happened for me on MariaDB.

For example:

Create table if not exists CADASTRO_MAQUINAS ( Id VARCHAR(16), Primary Key (Id) );

Create table if not exists INFOS ( Id_Maquina VARCHAR(16) NOT NULL, CONSTRAINT FK_infos_cadastro_maquinas Foreign Key (Id_Maquina) references CADASTRO_MAQUINAS(Id) );

If I try to create the second table using cadastro_maquinas (lower cases) instead of CADASTRO_MAQUINAS, I will receive this error.

Answer 4

I got this error while trying to use a foreign key to reference a non-unique field. (which apparently is not allowed)

Answer 5

In very strange cases your database might be broken. In my case I did not have any foreign keys on the table and the only renaming the table or changing engine helped.

Turned out innoDB was broken, see: https://dba.stackexchange.com/questions/86853/1025-error-on-rename-of-table-errno-150-table-was-deleted-while-tried-to-a?lq=1

Answer 6

Always create master/parent tables first, and then create your detail/child tables.