Error message on MySql:
Illegal mix of collations (utf8_unicode_ci,IMPLICIT) and (utf8_general_ci,IMPLICIT) for operation '='
I have gone through several other posts and was not able to solve this problem. The part affected is something similar to this:
CREATE TABLE users (
userID INT UNSIGNED NOT NULL AUTO_INCREMENT,
firstName VARCHAR(24) NOT NULL,
lastName VARCHAR(24) NOT NULL,
username VARCHAR(24) NOT NULL,
password VARCHAR(40) NOT NULL,
PRIMARY KEY (userid)
) ENGINE = INNODB CHARACTER SET utf8 COLLATE utf8_unicode_ci;
CREATE TABLE products (
productID INT UNSIGNED NOT NULL AUTO_INCREMENT,
title VARCHAR(104) NOT NULL,
picturePath VARCHAR(104) NULL,
pictureThumb VARCHAR(104) NULL,
creationDate DATE NOT NULL,
closeDate DATE NULL,
deleteDate DATE NULL,
varPath VARCHAR(104) NULL,
isPublic TINYINT(1) UNSIGNED NOT NULL DEFAULT '1',
PRIMARY KEY (productID)
) ENGINE = INNODB CHARACTER SET utf8 COLLATE utf8_unicode_ci;
CREATE TABLE productUsers (
productID INT UNSIGNED NOT NULL,
userID INT UNSIGNED NOT NULL,
permission VARCHAR(16) NOT NULL,
PRIMARY KEY (productID,userID),
FOREIGN KEY (productID) REFERENCES products (productID) ON DELETE RESTRICT ON UPDATE NO ACTION,
FOREIGN KEY (userID) REFERENCES users (userID) ON DELETE RESTRICT ON UPDATE NO ACTION
) ENGINE = INNODB CHARACTER SET utf8 COLLATE utf8_unicode_ci;
The stored procedure I'm using is this:
CREATE PROCEDURE updateProductUsers (IN rUsername VARCHAR(24),IN rProductID INT UNSIGNED,IN rPerm VARCHAR(16))
BEGIN
UPDATE productUsers
INNER JOIN users
ON productUsers.userID = users.userID
SET productUsers.permission = rPerm
WHERE users.username = rUsername
AND productUsers.productID = rProductID;
END
I was testing with php, but the same error is given with SQLyog. I have also tested recreating the entire DB but to no good.
Any help will be much appreciated.
The default collation for stored procedure parameters is utf8_general_ci
and you can't mix collations, so you have four options:
Option 1: add COLLATE
to your input variable:
SET @rUsername = ‘aname’ COLLATE utf8_unicode_ci; -- COLLATE added
CALL updateProductUsers(@rUsername, @rProductID, @rPerm);
Option 2: add COLLATE
to the WHERE
clause:
CREATE PROCEDURE updateProductUsers(
IN rUsername VARCHAR(24),
IN rProductID INT UNSIGNED,
IN rPerm VARCHAR(16))
BEGIN
UPDATE productUsers
INNER JOIN users
ON productUsers.userID = users.userID
SET productUsers.permission = rPerm
WHERE users.username = rUsername COLLATE utf8_unicode_ci -- COLLATE added
AND productUsers.productID = rProductID;
END
Option 3: add it to the IN
parameter definition:
CREATE PROCEDURE updateProductUsers(
IN rUsername VARCHAR(24) COLLATE utf8_unicode_ci, -- COLLATE added
IN rProductID INT UNSIGNED,
IN rPerm VARCHAR(16))
BEGIN
UPDATE productUsers
INNER JOIN users
ON productUsers.userID = users.userID
SET productUsers.permission = rPerm
WHERE users.username = rUsername
AND productUsers.productID = rProductID;
END
Option 4: alter the field itself:
ALTER TABLE users CHARACTER SET utf8 COLLATE utf8_general_ci;
Unless you need to sort data in Unicode order, I would suggest altering all your tables to use utf8_general_ci
collation, as it requires no code changes, and will speed sorts up slightly.
UPDATE: utf8mb4/utf8mb4_unicode_ci is now the preferred character set/collation method. utf8_general_ci is advised against, as the performance improvement is negligible. See https://stackoverflow.com/a/766996/1432614