为什么我的查询不起作用？

Question

这是我的查询：

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'！问题是什么？

Answer 1

一些评论有关查询：

• 你可能想union all而不是union。如果两行碰巧具有完全相同的三个字段，我怀疑你想删除其中的一个。
• 您的where条款是多余的。

（这是除了order by问题。）

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; 

注意，这会给你多行。如果你想要一个总数，然后在聚合前做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; 

Answer 2

UNION关键字前面不能有ORDER BY子句。

如果要通过设置以及COUNT（*）记录命令，你可以添加一列这样的：

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