Can not add new column with foreign key - mysql

Question

I have a MySQL table and now I want to add a new column with Primary Key and Foreign Key.
What I've tried so far
How the table look like:
CREATE TABLE IF NOT EXISTS `results` (
`id` int(20) NOT NULL UNIQUE AUTO_INCREMENT,
`resultA_id` int(20) NOT NULL,
`resultB_id` int(20) NOT NULL,
`resultC_id` int(20) NOT NULL,
`resultD_id` int(20) NOT NULL,
`resultE_id` int(20) NOT NULL,
`resultF_id` int(20) NOT NULL,
FOREIGN KEY (resultA_id) REFERENCES resultA(id),
FOREIGN KEY (resultB_id) REFERENCES resultB(id),
FOREIGN KEY (resultC_id) REFERENCES resultC(id),
FOREIGN KEY (resultD_id) REFERENCES resultD(id),
FOREIGN KEY (resultE_id) REFERENCES resultE(id),
FOREIGN KEY (resultF_id) REFERENCES resultF(id),
PRIMARY KEY (`resultA_id`, `resultB_id`, `resultC_id`, `resultD_id`, `resultE_id`)
) ENGINE=InnoDB DEFAULT CHARSET=ascii COLLATE=ascii_bin;
How such e.g. a resultA table look like
CREATE TABLE IF NOT EXISTS `resultA` (
`id` int(20) NOT NULL AUTO_INCREMENT,
`name` varchar(100) NOT NULL UNIQUE,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=ascii COLLATE=ascii_bin;
Now I want to add a new Column to results with a relation to a new table called table_test. Therefor I've created a new table_test
CREATE TABLE IF NOT EXISTS `table_test` (
`id` int(20) NOT NULL AUTO_INCREMENT,
`name` varchar(100) NOT NULL UNIQUE,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=ascii COLLATE=ascii_bin;
Than added a new column to results
ALTER TABLE results ADD COLUMN test_id;
Now I want to add a primary key
ALTER TABLE `results` ADD PRIMARY KEY(`test_id`);
And I got this error
Cannot drop index 'PRIMARY': needed in a foreign key constraint
I've also tried to add a foreign key like this here
ALTER TABLE `results` ADD CONSTRAINT `results_ibfk_7` FOREIGN KEY (`test_id`) REFERENCES `table_test`(`id`) ON DELETE RESTRICT ON UPDATE RESTRICT;
and than I got this error
Cannot add or update a child row: a foreign key constraint fails
I've tried to ignore the foreign key check like this here
SET FOREIGN_KEY_CHECKS=0
But this does not help.
I've also tried to create a new table with the new column and than try to copy the data from the old table to the new one
INSERT INTO results_new SELECT * FROM results;
Than I also got this error here
Cannot add or update a child row: a foreign key constraint fails
What can I do or what I'm doing wrong here?
EDIT
What I've done is now. Creating the new table with the new column and foreign key and so on. Than dump the old table to a CSV file. Edit this CSV file and add the new value to every line in the csv file. Import this CSV file into the new table. This works!
Thanks all for your help!

Answer 1

I think what you are trying to do is to add the test_id field to the primary key for table results.
As stated here (source question), you cannot do that with SQLite.
If you want to do that with MySQL, you have to drop the exsisting primary key and recreate it (source).
ALTER TABLE MyTable
DROP PRIMARY KEY,
ADD PRIMARY KEY (old_col1, old_col2, new_col);