Question

我正在使用下面的代码，这些代码在mysql中执行，但是在通过java程序时遇到错误，因为java程序无法读取分号...对于Java，这是3条语句。我需要执行此查询（设置两个变量，然后在一个查询中选择）：

set @row_number:=0;set @PROMOTION_ID_NO:='';
SELECT 
     @row_number:=CASE 
        WHEN @PROMOTION_ID_NO=PD.PROMOTION_ID THEN @row_number + 1
        ELSE 1
    END AS SEQ,
     @PROMOTION_ID_NO:=PD.PROMOTION_ID AS PROMOTION_ID,
    PD.CONDITION_CODE,
    PM.PROMOTION_code,
    PD.CONDITION_TYPE
FROM
    POS_PROMOTION_DISCOUNT PD , POS_PROMOTION_MASTER PM WHERE 
    PD.PROMOTION_ID = PM.PROMOTION_ID
AND PD.STORE_NO = 'G121';

Answer 1

您可以将SET语句移到单独的Derived Table，然后与其他表一起对该表进行CROSS JOIN。
请不要使用基于旧逗号的隐式联接，而不要使用现代Explicit Join based syntax。我已改为使用JOIN .. ON。

请尝试以下操作：

SELECT 
     @row_number:=CASE 
                    WHEN @PROMOTION_ID_NO=PD.PROMOTION_ID THEN @row_number + 1
                    ELSE 1
                  END AS SEQ,
     @PROMOTION_ID_NO:=PD.PROMOTION_ID AS PROMOTION_ID,
    PD.CONDITION_CODE,
    PM.PROMOTION_code,
    PD.CONDITION_TYPE
FROM
    POS_PROMOTION_DISCOUNT PD 
JOIN POS_PROMOTION_MASTER PM ON PD.PROMOTION_ID = PM.PROMOTION_ID
CROSS JOIN (SELECT row_number:=0, @PROMOTION_ID_NO:='') AS user_init 
WHERE 
  PD.STORE_NO = 'G121';

在SELECT语句中设置两个变量-MySQL

1 个答案: