Using adminer editor on a (InnoDB) table with foreign key having attribute ON DELETE SET NULL it is not possible to insert a record with a NULL value for this foreign key field.
So this is a problem for 'optional 1-n relations'.
If the field allows NULL (it isn't NOT NULL) then you can insert a record with a NULL value by selecting nothing in the foreign key option list.
Using Adminer there is no problem inserting a record having null value for the foreign key. (the field allows NULL).
But Editor complains about the foreign key constraint when selecting nothing from the option list and insert.
So we are experiencing different behaviour. Any clue?
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Please attach a dump and describe the table and column which Editor is complaining about.
Please see attached files.
The problem is in the varchar ID. There is no option to differentiate between the NULL value and an empty string in <select>. The solution would be to create another <select> or checkbox just for selecting the empty value but it is not very user friendly. Do you have another idea?
Translating the empty string to NULL would be a solution that is intuitive and comparable to INT keys.
Emptystring as a referenced key value is a bad idea anyway. If that is realy what you want you can use adminer for these inserts.
Thank you for the report, I've fixed it in Git. You can download the "Current development version" from http://www.adminer.org/en/#download
I agree. I've changed the behavior so that now it is not possible to link empty-string foreign key in the NULL field.
Jakub, thank you very much for this quick fix.