操作'='的排序规则（utf8_unicode_ci，IMPLICIT）和（utf8_general_ci，IMPLICIT）的非法混合

Question

MySql上的错误消息：

Illegal mix of collations (utf8_unicode_ci,IMPLICIT) and (utf8_general_ci,IMPLICIT) for operation '='

我浏览了其他几篇文章，但无法解决此问题。受影响的部分与此类似：

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;

我正在使用的存储过程是这样的：

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

我在用php测试，但是SQLyog给出了相同的错误。我还测试了重新创建整个数据库，但效果不佳。

任何帮助都感激不尽。

Answer 1

存储过程参数的默认排序规则为utf8_general_ci并且您不能混合排序规则，因此有四个选项：

选项1 ：添加COLLATE到您的输入变量中：

SET @rUsername = ‘aname’ COLLATE utf8_unicode_ci; -- COLLATE added
CALL updateProductUsers(@rUsername, @rProductID, @rPerm);

选项2 ：COLLATE在WHERE条款中添加：

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

选项3 ：将其添加到IN参数定义中：

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

选项4 ：更改字段本身：

ALTER TABLE users CHARACTER SET utf8 COLLATE utf8_general_ci;

除非您需要按Unicode顺序对数据进行排序，否则我建议您更改所有表以使用 utf8_general_ci排序规则，因为它不需要更改代码，并且会稍微加快排序速度。

更新 ：utf8mb4 /
utf8mb4_unicode_ci现在是首选的字符集/排序规则方法。建议不要使用utf8_general_ci，因为性能提升可忽略不计。参见https://stackoverflow.com/a/766996/1432614