Question

这是我的疑问：

SELECT [MsgType],sr.ServiceName,content,COUNT(*) AS Occurrence
 FROM [VSReceiveSend].[dbo].[ReceiveBuffer] rb
   INNER JOIN dbo.Services sr ON rb.ServiceCode=sr.Code
 where MsgType is not null and MsgType = 2
 group by MsgType,CONTEnt, sr.ServiceName
 order by COUNT(*) DESC

UNION

SELECT [MsgType],sr.ServiceName,content,COUNT(*) AS Occurrence
 FROM [VSReceiveSend].[dbo].ReceivedSMS rb
   INNER JOIN dbo.Services sr ON rb.ServiceCode=sr.Code
where MsgType is not null and MsgType = 2
group by MsgType,CONTEnt, sr.ServiceName
order by COUNT(*) DESC

sql给我这个错误：Incorrect syntax near the keyword 'UNION'！有什么问题？

Answer 1

在UNION关键字之前不能有ORDER BY子句。

如果您想按记录集和COUNT（*）订购，可以添加如下列：

SELECT [MsgType],sr.ServiceName,content,COUNT(*) AS Occurrence, 1 AS recordset_order
 FROM [VSReceiveSend].[dbo].[ReceiveBuffer] rb
   INNER JOIN dbo.Services sr ON rb.ServiceCode=sr.Code
 where MsgType is not null and MsgType = 2
 group by MsgType,CONTEnt, sr.ServiceName
UNION
SELECT [MsgType],sr.ServiceName,content,COUNT(*) AS Occurrence, 2 AS recordset_order
 FROM [VSReceiveSend].[dbo].ReceivedSMS rb
   INNER JOIN dbo.Services sr ON rb.ServiceCode=sr.Code
where MsgType is not null and MsgType = 2
group by MsgType,CONTEnt, sr.ServiceName
order by recordset_order ASC, COUNT(*) DESC

Answer 2

有关查询的一些评论：

您可能需要union all而不是union。如果两行恰好具有完全相同的三个字段，我怀疑你想要删除其中一个字段。
您的where条款是多余的。

（这是order by问题的补充。）

SELECT [MsgType], sr.ServiceName, content, COUNT(*) AS Occurrence
FROM [VSReceiveSend].[dbo].[ReceiveBuffer] rb INNER JOIN
     dbo.Services sr
     ON rb.ServiceCode =s r.Code
where MsgType = 2
group by content, sr.ServiceName
UNION ALL
SELECT [MsgType], sr.ServiceName, content, COUNT(*) AS Occurrence
FROM [VSReceiveSend].[dbo].ReceivedSMS rb INNER JOIN
      dbo.Services sr
      ON rb.ServiceCode = sr.Code
where MsgType = 2
group by MsgType, content, sr.ServiceName
order by Occurrence DESC;

请注意，这将为您提供多行。如果您想要整体计数，请在聚合之前执行union all：

SELECT MsgType, sr.ServiceName, content, COUNT(*) AS Occurrence
FROM (select msgtype, servicecode, content
      from [VSReceiveSend].[dbo].[ReceiveBuffer] rb 
      where MsgType = 2
      union all
      select
      from  [VSReceiveSend].[dbo].ReceivedSMS rb
      where MsgType = 2
     ) rb INNER JOIN
     dbo.Services sr
     ON rb.ServiceCode = sr.Code
group by MsgType, content, sr.ServiceName
order by Occurrence DESC;

为什么我的查询不起作用？

2 个答案: