Question

I have joined three tables into a view, and then i try to update the view and get this error

#1393 - Can not modify more than one base table through a join view

ER_VIEW_MULTIUPDATE

I understand the error. I cannot update multiple tables at once.

HOWEVER… I have done this before. Last week to be precise, on the same machine, same mysql installation.

I promise you that I have joined together tables through a view before (the same tables infact) and updated the view with no problems.

Does anybody know why its not working?

The PHP code that worked last week

"UPDATE administrators AS a INNER JOIN user_types AS ut ON a.admin_id = ut.type_id INNER JOIN users AS u ON u.user_id = ut.user_id SET a.firstname = '{$user_input["firstname"]}', a.surname = '{$user_input["surname"]}', u.email_address = '{$user_input["email_address"]}' WHERE u.user_id = {$user_input["user_id"]}"

The SQL code im trying now

CREATE VIEW admin_users AS
SELECT administrators ad
    JOIN user_types ut
        ON ad.admin_id = ut.type_reference
    JOIN users us
        ON ut.user_id = us.user_id
WHERE ut.user_type = 'ADMIN'

UPDATE admin_users
SET
    firstname = 'alex2',
    surname = 'finch2',
    email_address = '[e-mail]'
WHERE
    user_id = 2

Answer 1

The SQL that worked last week was a direct UPDATE query that modified tables, whereas you’re now attempting to UPDATE those same tables through a view. That’s the change. With a VIEW, you can only update one table at a time. You might look into stored procedures if you want to update multiple tables with one query.

Something like this:

DELIMITER //
CREATE PROCEDURE updateUser(
    var_user_id INT,
    var_firstname VARCHAR(32),
    var_surname VARCHAR(32),
    var_email_address VARCHAR(128)
)
BEGIN
    UPDATE administrators AS a 
        INNER JOIN user_types AS ut 
            ON a.admin_id = ut.type_id 
        INNER JOIN users AS u 
            ON u.user_id = ut.user_id 
        SET a.firstname = var_firstname, 
            a.surname = var_surname, 
            u.email_address = var_email_address 
    WHERE u.user_id = var_user_id;
END//

To call:

CALL updateUser( '$user_id', '$firstname', '$surname', '$email_address' );