Question

我无法在嵌套选择中使用CASE语句。我想我很接近，但我不能完全正确地理解语法。到目前为止，我已经尝试过：

SELECT l.*,
Credit = (
CASE WHEN ISNULL(M.POSTCODE,'') <> '' THEN
  sum(Credit) from Balance cb Where LEFT(LTrim(cb.AccountHolder),4) LIKE LEFT(LTrim(m.Company),4)
 ELSE
 sum(Credit) from Balance cb Where LEFT(LTrim(cb.AccountHolder),4) LIKE LEFT(LTrim(m.Company),4) 
 END 
)
FROM live l INNER JOIN master m on m.ClientID = L.ClientID 
WHERE ClientID = 12345

还有：

SELECT l.*,
(SELECT
CASE WHEN ISNULL(M.POSTCODE,'') <> '' THEN
  sum(Credit) from Balance cb Where LEFT(LTrim(cb.AccountHolder),4) LIKE LEFT(LTrim(m.Company),4)
 ELSE
 sum(Credit) from Balance cb Where LEFT(LTrim(cb.AccountHolder),4) LIKE LEFT(LTrim(m.Company),4) 
 END 
) AS Credit
FROM live l INNER JOIN master m on m.ClientID = L.ClientID 
WHERE ClientID = 12345

这似乎与http://msdn.microsoft.com/en-us/library/ms181765.aspx的MSDN示例相匹配。我错过了什么吗？

Answer 1

我认为你需要在sum子查询之前添加一些选择。

SELECT l.*,
Credit = (
   CASE WHEN ISNULL(M.POSTCODE,'') <> '' THEN
     (SELECT sum(Credit) from Balance cb Where LEFT(LTrim(cb.AccountHolder),4) LIKE LEFT(LTrim(m.Company),4))
   ELSE
     (SELECT sum(Credit) from Balance cb Where LEFT(LTrim(cb.AccountHolder),4) LIKE LEFT(LTrim(m.Company),4))
   END 
) 
FROM live l 
    INNER JOIN master m on m.ClientID = L.ClientID 
WHERE ClientID = 12345

您的选择也完全相同，因此除非您打算让它们与众不同，否则不需要案例。

Answer 2

SELECT l.*,
      CASE 
         WHEN ISNULL(M.POSTCODE,'') <> '' THEN
             (SELECT sum(Credit) 
             from Balance cb 
             Where LEFT(LTrim(cb.AccountHolder),4) LIKE LEFT(LTrim(m.Company),4))
         ELSE
             (SELECT sum(Credit) 
             from Balance cb 
             Where LEFT(LTrim(cb.AccountHolder),4) LIKE LEFT(LTrim(m.Company),4) )
       END as 'Credit'
FROM live l  INNER JOIN master m 
       on m.ClientID = L.ClientID 
WHERE ClientID = 12345

嵌套选择中的大小写

2 个答案: