MySQL on子句中的未知列

Question

我想訪問MySQL子查詢中的字段，但是'var_customer_id' in 'on clause'錯誤中得到了未知列'var_customer_id' in 'on clause' 。 這是我的代碼：

SELECT *,
        CONCAT(customer_phone_1, ', ', customer_phone_2) AS customer_phone,
        CONCAT(customer_fax_1, ', ', customer_fax_2) AS customer_fax,
        CONCAT(customer_email_1, ', ', customer_email_2) AS customer_email,
        tbl_customer.customer_id AS var_customer_id,                
        (
            SELECT
                GROUP_CONCAT(tbl_service.service_name SEPARATOR ', ')
            FROM
                kuesioner_bbia.tbl_customer_service
                INNER JOIN kuesioner_bbia.tbl_service 
                ON (tbl_customer_service.service_id = tbl_service.service_id )
                AND tbl_customer_service.customer_id=var_customer_id                    
            GROUP BY tbl_customer_service.customer_id                   
            )               

        FROM tbl_customer
        ORDER BY customer_id ASC

那么如何解決呢？ 對不起我的英語不好。

Answer 1

錯誤在這里：

ON (tbl_customer_service.service_id = tbl_service.service_id )
                AND tbl_customer_service.customer_id=var_customer_id   

可以是以下任意一種（注意：我用var_customer_id替換了tbl_customer.customer_id ）：

ON (tbl_customer_service.service_id = tbl_service.service_id )
WHERE tbl_customer_service.customer_id = tbl_customer.customer_id

或（重新定位右括號）：

ON (tbl_customer_service.service_id = tbl_service.service_id 
AND tbl_customer_service.customer_id = tbl_customer.customer_id)