I've a table CustomizationSet with the columns:
customization_set_guid (which is a non-nullable guid and also the primary key)
creator_account_guid
and a few others
And a table with existing data Registration with the columns:
registration_id (an int and the primary key)
customization_set_guid (also a guid (so a char(36)) which is nullable, and all entries are currently null)
and a few other columns
When I try and run
ALTER TABLE Registration ADD FOREIGN KEY
(
customization_set_guid
) REFERENCES CustomizationSet (
customization_set_guid
);
in MySQL Workbench, it gives the error 1050Table '.\dbname\registration' already exists.
If I try to use the UI to add the foreign keys with the Foreign Keys tab of the Alter Table Dialog, and choose CustomizationSet as the referenced table, it doesn't let me choose customization_set_guid in the list of columns.
I'm really not sure why it won't let me add this foreign key. I've just successfully created foreign keys between tables I just added. The Registration table has existed for awhile...
I got the same error, and it was due to the fact that the foreign key already existed. What you want is just to add the constraint:
ALTER TABLE Registration
ADD CONSTRAINT idx_Registration_CustomizationSet
FOREIGN KEY (customization_set_guid)
REFERENCES CustomizationSet(customization_set_guid);