Oracle PL/SQL查询顺序问题与Distinct有关

有谁知道这个查询有什么问题？

 SELECT DISTINCT c.CN as ClaimNumber, 
         a.ItemDate as BillReceivedDate, c.DTN as
 DocTrackNumber
         FROM ItemData a,
         ItemDataPage b,
         KeyGroupData c
         WHERE a.ItemTypeNum in (112, 113, 116, 172, 189)
         AND a.ItemNum = b.ItemNum
         AND b.ItemNum = c.ItemNum
         ORDER BY a.DateStored DESC;

我在职业生涯的大部分时间都做过T-Sql,这对我来说是正确的,但是这个查询是针对Oracle数据库而Toad只是将光标放在Order By部分的a.DateStored上.我确信这对于任何做PL/SQL的人都是基本的.

谢谢!

[编辑]为了将来参考,SQL*Plus给出的错误是:"ORA-01791:不是SELECTed表达式"

您需要修改查询:

SELECT DISTINCT c.CN as ClaimNumber, 
         a.ItemDate as BillReceivedDate, c.DTN as
 DocTrackNumber, a.DateStored
         FROM ItemData a,
         ItemDataPage b,
         KeyGroupData c
         WHERE a.ItemTypeNum in (112, 113, 116, 172, 189)
         AND a.ItemNum = b.ItemNum
         AND b.ItemNum = c.ItemNum
         ORDER BY a.DateStored DESC;

在进行DISTINCT时,您的订单需要是所选列之一.