Question

在SQL Server 2008中，我有一个如下所示的表：

ID |  RefNum   |  Label        |   Value  |  Status
------------------------------------------------------
1       123      OrderNum         123456       0
2       123      TrackingNum      111111       0
3       123      ConfNum          989898       0
4       234      OrderNum         234567       1
5       234      TrackingNum      222222       1
6       234      ConfNum          878787       0
7       567      OrderNum         345678       1
8       567      TrackingNum      333333       0
9       567      ConfNum          767676       0

我想选择Status = 0的所有记录，并根据RefNum连接到'OrderNum'和'TrackingNum'标签值，无论'OrderNum'和TrackingNum状态是1还是0。例如，查询应该产生：

ID |  RefNum   |  Label        |   Value  | Status |OrderNum|TrackingNum
------------------------------------------------------------------------
1       123      OrderNum         123456       0    123456   111111
2       123      TrackingNum      111111       0    123456   111111
3       123      ConfNum          989898       0    123456   111111
6       234      ConfNum          878787       0    234567   222222
8       567      TrackingNum      333333       0    345678   333333
9       567      ConfNum          767676       0    345678   333333

现在，我的查询如下：

SELECT                  Id
               ,mT.RefNum
               ,Label
               ,Value
               ,Status
               ,OrderNum
               ,TrackingNum
FROM [dbo].[myTable] AS mT
INNER JOIN (
    SELECT MAX(ID) As OrderRowId, RefNum, Value AS OrderNum
    FROM [dbo].[myTable]
    WHERE Label= 'OrderNum'
    group by RefNum, Value) AS OrderNums
    ON OrderNums.RefNum= mt.RefNum
INNER JOIN (
    SELECT MAX(ID) As OrderRowId, RefNum, Value AS TrackingNum
    FROM [dbo].[myTable]
    WHERE Label= 'TrackingNum'
    group by RefNum, Value) AS TrackingNums
    ON TrackingNums.RefNum= mt.RefNum
WHERE ProcessComplete = 0

这可用于工作，但需要散列连接。希望有人在这方面打洞或提供更有效的解决方案。感谢。

Answer 1

如果每个参考号不能有重复的订单号或跟踪号，您可以使用常规LEFT JOIN或JOIN稍微简化查询;

SELECT mt.id, mt.refnum, mt.label, mt.value, mt.status,
       ordno.value ordernum, trackno.value trackingnum
FROM myTable mt
LEFT JOIN myTable ordno
  ON ordno.label='ordernum' and mt.refnum=ordno.refnum
LEFT JOIN myTable trackno
  ON trackno.label='trackingnum' and mt.refnum=trackno.refnum
WHERE mt.status = 0;

An SQLfiddle to test with

如果可能存在重复项，您仍然可以执行一次GROUP BY来获得结果;

SELECT mt.id, mt.refnum, mt.label, mt.value, mt.status,
       MAX(ordno.value) ordernum, MAX(trackno.value) trackingnum
FROM myTable mt
LEFT JOIN myTable ordno
  ON ordno.label='ordernum' and mt.refnum=ordno.refnum
LEFT JOIN myTable trackno
  ON trackno.label='trackingnum' and mt.refnum=trackno.refnum
WHERE mt.status = 0
GROUP BY mt.id,mt.refnum,mt.label,mt.value,mt.status;

Another SQLfiddle

SQL组和加入

1 个答案: