Question

我的数据库中有一个表（tbl_MatterItem），用于跟踪项目的发送和接收日期。如果尚未发送或接收，则值为NULL。我有另一个链接到的表（tbl_Matter），以获取该特定项目的BillingLawyer。

BillingLawyer     ItemSent     ItemReceived
-------------     --------     ------------
   Alison         09/09/09        NULL
   Alison         10/10/10        NULL
   Alison         11/11/11       13/11/11
   Alison         12/12/12        NULL

我想为每位律师检索一行，包括他们的姓名，发送的物品数量以及收到的物品数量。

BillingLawyer    Sent    Received
-------------    -----   --------
   Alison         4         1

以下是我到目前为止：

SELECT BillingLawyer, 
(SELECT COUNT(DISTINCT itemSent)FROM tbl_matteritem mit WHERE itemid=2 AND itemSent IS NOT NULL AND mit.ItemSent= mi.itemSent) AS [Sent], 
(SELECT COUNT(DISTINCT itemReceived)FROM tbl_matteritem mitm WHERE itemid=2 AND itemReceived IS NOT NULL AND mitm.itemreceived = mi.itemreceived)AS Received
FROM tbl_matteritem mi JOIN tbl_matter m ON mi.matterid = m.matterid
GROUP BY BillingLawyer, ItemSent, itemreceived
ORDER BY 1

但是我的结果显示有一个额外的记录，看起来是什么位值？：

BillingLawyer    Sent    Received
-------------    ----    --------
   Alison         0         0
   Alison         1         1
   Alison         1         0
   Alison         1         0
   Alison         1         0

我出错的任何想法？

Answer 1

试试这个：

SELECT
    BillingLawyer,
    SUM(CASE WHEN ItemSent IS NOT NULL THEN 1 ELSE 0 END) AS Sent,
    SUM(CASE WHEN ItemReceived IS NOT NULL THEN 1 ELSE 0 END) AS Received
FROM
    tbl_matteritem mi
JOIN tbl_matter m ON
    mi.matterid = m.matterid
GROUP BY BillingLawyer
ORDER BY BillingLawyer

Answer 2

您在ItemSent上进行分组，因此count(distinct ItemSent）将返回1或0.毕竟，将为ItemSent的每个不同值创建一个新组，然后count()将应用于该组。

如果您想按BillingLawyer计算项目，请在BillingLawyer上分组，而不是ItemSent。

Answer 3

我首先删除DISTINCT，因为它会计入每个日期。

SELECT BillingLawyer, 
(SELECT COUNT( itemSent)FROM tbl_matteritem mit WHERE itemid=2 AND itemSent IS      NOT NULL AND mit.ItemSent= mi.itemSent) AS [Sent], 
(SELECT COUNT( itemReceived)FROM tbl_matteritem mitm WHERE itemid=2 AND itemReceived IS NOT NULL AND mitm.itemreceived = mi.itemreceived)AS Received
FROM tbl_matteritem mi JOIN tbl_matter m ON mi.matterid = m.matterid
GROUP BY BillingLawyer, ItemSent, itemreceived
ORDER BY 1

Answer 4

请勿在{{1}}中加入ItemSent, itemreceived。仅使用GROUP BY

多个Sql计数

4 个答案: