使用WooCommerce的'on子句'SQL查询中的未知列'O.order_id'

Question

我在下面的查询返回以下错误消息“'on clause'中的未知列'O.order_id'”。我猜这是一个优先问题？但我没有足够的背景来弄清楚可能的位置。

我刚刚添加了'where'子句，以便我可以过滤产品类别。

SELECT
    MAX(
        CASE WHEN OIM.meta_key = 'enrolment_id' THEN(
        SELECT
            firstname
        FROM
            wp_sp_enrolments E
        WHERE
            OIM.meta_value = E.id
    )
    END
) AS 'firstname',
MAX(
    CASE WHEN OIM.meta_key = 'enrolment_id' THEN(
    SELECT
        surname
    FROM
        wp_sp_enrolments E
    WHERE
        OIM.meta_value = E.id
)
END
) AS 'surname',
O.order_item_name AS 'school',
MAX(
    CASE WHEN OIM.meta_key = 'class' THEN OIM.meta_value
END
) AS 'class',
MAX(
    CASE WHEN OIM.meta_key = 'fee-type' THEN OIM.meta_value
END
) AS 'fees',
MAX(
    CASE WHEN OIM.meta_key = 'enrolment_Id' THEN(
    SELECT
        UM.meta_value
    FROM
        wp_usermeta UM,
        wp_sp_enrolments E
    WHERE
        UM.meta_key = '_user_phone' AND UM.user_id = E.memberid AND E.id = OIM.meta_value
    LIMIT 1
)
END
) AS 'phone', MAX(
    CASE WHEN OIM.meta_key = 'enrolment_id' THEN(
    SELECT
        U.user_email
    FROM
        wp_users U,
        wp_sp_enrolments E
    WHERE
        U.id = E.memberid AND E.id = OIM.meta_value
    LIMIT 1
)
END
) AS 'email', P.post_status AS 'status'
FROM
    wp_woocommerce_order_items O,
    wp_terms T,
    wp_term_taxonomy TT,
    wp_term_relationships TR,
    wp_woocommerce_order_itemmeta OIM
INNER JOIN wp_posts P ON
    P.ID = O.order_id
WHERE
    T.name = 'workshops' AND T.term_id = TT.term_id AND TT.taxonomy = 'product_cat' AND TT.term_id = TR.term_taxonomy_id AND TR.object_id = OIM.meta_value AND OIM.meta_key = '_product_id' AND OIM.order_item_id = O.order_item_id
GROUP BY
    O.order_item_id

Answer 1

问题是，如您所怀疑的，逗号运算符和连接运算符的优先级。

在https://dev.mysql.com/doc/refman/8.0/en/join.html上声明：

但是，逗号运算符的优先级小于INNER JOIN，CROSS JOIN，LEFT JOIN等的优先级。如果在存在连接条件时将逗号连接与其他连接类型混合，则可能会出现'on子句'中未知列'col_name'形式的错误。

意思是，你不应该混合，最好。

所以不是内联，而是

, wp_posts P

在WHERE

and P.id=O.order_id and P.id is not null

或者，您可以将逗号分隔的表捆绑在括号中：

(wp_woocommerce_order_items O,
wp_terms T,
wp_term_taxonomy TT,
wp_term_relationships TR,
wp_woocommerce_order_itemmeta OIM  )
INNER JOIN ...

另一个例子，为什么我对逗号运算符有如此强烈的厌恶。

Answer 2

不确定，但尝试以下做INNER JOIN：

SELECT
    MAX(
        CASE WHEN OIM.meta_key = 'enrolment_id' THEN(
        SELECT
            firstname
        FROM
            wp_sp_enrolments E
        WHERE
            OIM.meta_value = E.id
    )
    END
) AS 'firstname',
MAX(
    CASE WHEN OIM.meta_key = 'enrolment_id' THEN(
    SELECT
        surname
    FROM
        wp_sp_enrolments E
    WHERE
        OIM.meta_value = E.id
)
END
) AS 'surname',
O.order_item_name AS 'school',
MAX(
    CASE WHEN OIM.meta_key = 'class' THEN OIM.meta_value
END
) AS 'class',
MAX(
    CASE WHEN OIM.meta_key = 'fee-type' THEN OIM.meta_value
END
) AS 'fees',
MAX(
    CASE WHEN OIM.meta_key = 'enrolment_Id' THEN(
    SELECT
        UM.meta_value
    FROM
        wp_usermeta UM,
        wp_sp_enrolments E
    WHERE
        UM.meta_key = '_user_phone' AND UM.user_id = E.memberid AND E.id = OIM.meta_value
    LIMIT 1
)
END
) AS 'phone', MAX(
    CASE WHEN OIM.meta_key = 'enrolment_id' THEN(
    SELECT
        U.user_email
    FROM
        wp_users U,
        wp_sp_enrolments E
    WHERE
        U.id = E.memberid AND E.id = OIM.meta_value
    LIMIT 1
)
END
) AS 'email', P.post_status AS 'status'
FROM wp_woocommerce_order_items O
INNER JOIN wp_woocommerce_order_itemmeta OIM ON
    O.order_item_id = OIM.order_item_id 
INNER JOIN wp_term_relationships TR ON
    O.order_id = OIM.meta_value
INNER JOIN wp_term_taxonomy TT ON
    TR.term_taxonomy_id = TT.term_taxonomy_id
INNER JOIN wp_terms T ON
    T.term_id = TT.term_id 
INNER JOIN wp_posts P ON
    P.ID = O.order_id
WHERE T.name = 'workshops' 
    AND TT.taxonomy = 'product_cat' 
    AND OIM.meta_key = '_product_id'
GROUP BY
    O.order_item_id