多个Sql计数

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，则该值为空。我有另一个表（tbl_事项），我正在链接到该表，以获取该特定项目的付费律师

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

我想为每个律师检索一行，其中包含他们的姓名、发送的项目数量和接收的项目数量

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

以下是我目前的情况：

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

然而，我的结果显示了一个额外的记录和什么似乎是位值

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

你知道我哪里出错了吗？

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

---

您正在对

itemssent

进行分组，因此

count（distinct itemssent

）将返回1或0。毕竟，将为

itemssent

的每个不同值创建一个新组，然后将

count（）

应用于该组

---

如果您想按

BillingLawyer

计算项目数，请按

BillingLawyer

分组，但不要按

项目发送

首先删除

不同的

，因为它将计算每个日期

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

---

不要将

itemssent、itemsreceived

包含在

分组依据中

。

---

仅使用

分组计费律师

+1最佳解决方案imho。您可以省略

else 0

：如果没有

else

，则不匹配的

大小写

返回

null

谢谢。我通常把它放在零位只是为了显得过于明显：）