Question

我正在尝试从CASE子句中使用WHERE条件的表中获取数据，目前我正在使用以下查询： -

SELECT count(enq_id) AS total, sum(purchase_amount) AS purchase
FROM temp_stock
WHERE purchase_date <> '0000-00-00'
AND purchase_date < '2012-08-01'
AND (

STATUS = 'Sold'
OR STATUS = 'In Stock'
OR STATUS = 'Ref'
)
AND CASE WHEN (

STATUS = 'Sold'
)
THEN delivery_date >= '2012-08-01'
END

但它会为0返回total，为NULL返回purchase。

Answer 1

来自your comment。

我想使用案例陈述，请你澄清一下where子句
中的案例陈述

您可以在CASE中使用WHERE语句，如下所示：

SELECT count(enq_id) AS total, sum(purchase_amount) AS purchase
FROM temp_stock
WHERE purchase_date <> '0000-00-00'
AND purchase_date < '2012-08-01'
AND (    STATUS = 'Sold'
      OR STATUS = 'In Stock'
      OR STATUS = 'Ref')
AND CASE STATUS 
         WHEN 'Sold' 
         THEN delivery_date >= '2012-08-01'
         ELSE 1=1
    END

您需要使用ELSE 1=1。否则你不会得到理想的结果。有关详细说明，请参阅this SQLFiddle

Answer 2

我不认为CASE可以这样工作。你想要的是一个稍微复杂的表达式作为你的WHERE子句。可能是这样的：

SELECT count(enq_id) AS total, sum(purchase_amount) AS purchase
FROM temp_stock
WHERE purchase_date <> '0000-00-00'
  AND purchase_date < '2012-08-01'
  AND (
     (STATUS = 'Sold' AND delivery_date >= '2012-08-01')
   OR STATUS = 'In Stock'
   OR STATUS = 'Ref'
 )

SQL WHERE子句中的CASE语句

2 个答案: