SELECT case when not exists(SELECT Cons_Date FROM sbcHisMaster WHERE HisTypeNO='L' AND ProductSN ='M7D2028')
THEN
(SELECT Cons_Date FROM sbcHisMaster WHERE HisTypeNO='Y' AND ProductSN ='M7D2028')
ELSE
(SELECT Cons_Date FROM sbcHisMaster WHERE HisTypeNO='L' AND ProductSN ='M7D2028')
END
判断某结果集为空 执行另一个语句 case when 巧妙用法
可随意转载,欢迎署名!