无法在MySQL Workbench中创建外键

Question

I have two tables, let's call em table1 and table2 .

• The Primary Key of table1 is CHAR(36), Not Null, and Unique.
• The column in table2 I'm trying to make an FK is, also, CHAR(36), Not Null, and Unique.
• Both tables have zero records.
• table1 has four Foreign Keys, all pointing at other tables. (None of them point at table2 .)

When I try to define the PK of table1 as an FK in table2 Workbench wouldn't let me select the field. The check box for the column in table2 simply would not be selected, no matter what I did.

Answer 1

In order to create this Foreign Key, I had to run it as a query directly, bypassing Workbench's GUI.

ALTER TABLE `my_schema`.`table_two` 
ADD INDEX `fk_to_table_one_pk_idx` (`table_two_column` ASC);
ALTER TABLE `my_schema`.`table_two` 
ADD CONSTRAINT `fk_to_table_one_pk`
    FOREIGN KEY (`table_two_column`)
    REFERENCES `my_schema`.`table_one` (`table_one_column`)
    ON DELETE RESTRICT
    ON UPDATE CASCADE;

I ran this query and, ta-friggin-da, the FK was in place and no error was thrown. I've heard that Workbench is pretty flaky and I think this confirms that.

After I had the FK in place I marked the column in table2 as the PK via the GUI without issue. The SQL might have worked just fine with the table2 column marked as the PK but I did not run it that way, so I cannot confirm that.

Answer 2

Try DISABLE KEYS or

SET FOREIGN_KEY_CHECKS=0;

make sure to

SET FOREIGN_KEY_CHECKS=1;

after.