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

问题：

Error message on MySql: MySql 上的错误消息：

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.我已经浏览了其他几个帖子，但无法解决这个问题。 The part affected is something similar to this: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;

The stored procedure I'm using is this:我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

I was testing with php, but the same error is given with SQLyog.我正在用 php 进行测试，但是 SQLyog 出现了同样的错误。 I have also tested recreating the entire DB but to no good.我还测试了重新创建整个数据库，但没有任何好处。

Any help will be much appreciated.任何帮助都感激不尽。

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解决方案：

参考一： https://en.stackoom.com/question/nNvu
参考二： https://stackoom.com/question/nNvu