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  • Illegal mix of collations (utf8mb4_unicode_ci,IMPLICIT) and (utf8_general_ci,COERCIBLE) for operation '='

    sql查询时报错:

    Illegal mix of collations (utf8_general_ci,IMPLICIT) and (utf8mb4_general_ci,COERCIBLE) for operation 'like'

    Illegal mix of collations (utf8mb4_unicode_ci,IMPLICIT) and (utf8_general_ci,COERCIBLE) for operation '='

    初步判断,数据库链接的编码 和 数据库sever的编码不同导致

    查看当前数据库默认编码:
    show variables where Variable_name like ‘collation%’;

    Variable_nameValue
    collation_connection utf8mb4_unicode_ci
    collation_database utf8mb4_general_ci
    collation_server utf8mb4_general_ci
     

    如果不想改数据库连接的编码,可以使用如下方法:

    在 ‘=’ 或 ‘like’ 前后添加    COLLATE utf8mb4_unicode_ci

    例如:

    SELECT
        d.a , d.a , d.*
    FROM
        (
            SELECT
                @num :=
            IF (
                @type = p.a COLLATE utf8mb4_unicode_ci and @type2 = p.b COLLATE utf8mb4_unicode_ci,
                @num + 1,
                1
            ) AS row_number,
            @type := p.a AS large,
            @type2 := p.b  as middle,
            p.*
        FROM
            entProduct p,
            (SELECT @num := 0, @type := '', @type2 := '') notuse
        WHERE
            p.entId = 12  COLLATE utf8mb4_unicode_ci
        AND p.deleted = 0  COLLATE utf8mb4_unicode_ci
        ORDER BY
            p.a ASC,
            p.b ASC
        ) d
    WHERE
        d.row_number <= 4;

    或  COLLATE  utf8mb4_general_ci

    只要确保 查询参数的编码统一即可

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  • 原文地址:https://www.cnblogs.com/yingsong/p/14613743.html
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