Question

我有两个sql查询（来自1个表）我需要加入但是当我尝试加入它时我总是收到错误。

第一张表：这是完整的表格。

Select Server, Network, ReservationIP, ReservationMAC, ReservationName
from ScopeReservations

结果（截断。这是一张非常表格）

> Server    Network ReservationIP   ReservationMAC  ReservationName
> Server1   10.3.64.32  10.3.64.36  000d5d08e83c    pr-bnea06-a01-a
> Server2   10.3.64.32  10.3.64.37  000d5d08278c    pr-bnea06-a02-a

第二张表：所有在ReservationMAC中具有重复值的人

 Select ReservationMAC, COUNT(*) from DHCP_ScopeReservations
    group by ReservationMAC
    having count(*) > 1
    order by ReservationMAC

结果：

ReservationMAC  (No column name)
0000850a3477    2
0000854b8328    2
85731867    2

我需要的结果就是这个。

Server  Network         ReservationIP   ReservationMAC  ReservationName
Server1 10.233.192.0    10.233.192.5    0000850a3477    pq2217a.
Server2 10.233.196.0    10.233.197.129  0000850a3477    pq2217.
Server1 10.80.16.0      10.80.17.13     0000854b8328    PQ090.
Server2 10.80.70.32     10.80.70.47     0000854b8328    Canon4B8328.

此外，结果不应包含具有相同reservationIP和reservationMAC的结果。不包括在结果中：

Server  Network     ReservationIP  ReservationMAC   ReservationName
Server1 10.34.57.0  10.34.57.10    011               vh101r
Server2 10.34.57.1  10.34.57.10    011               vh102r
Server1 10.206.0.0  10.206.3.22    0000681569af      ac-gpo069
Server2 10.206.0.0  10.206.3.22    0000681569af      ac-gpo069

结果应该是所有那些在ReservationMac列中有重复条目的人。结果必须包含表的所有列。

我试图做的事情：

Select a.Server, a.Network, a.ReservationIP, a.ReservationMAC,
a.ReservationName 
from DHCP_ScopeReservations a
INNER JOIN 
    (
        Select ReservationMAC, COUNT(*)
        from DHCP_ScopeReservations
        group by ReservationMAC
        having count(*) > 1
    ) dt ON a.ReservationMAC=dt.ReservationMAC

错误是

Msg 8155，Level 16，State 2，Line 6 没有为'dt'的第2列指定列名。

Answer 1

您需要声明COUNT(*)的别名：

Select a.Server, a.Network, a.ReservationIP, 
       a.ReservationMAC, a.ReservationName, dt.cnt 
from DHCP_ScopeReservations a   
INNER JOIN (Select ReservationMAC, COUNT(*) AS cnt
            from DHCP_ScopeReservations             
            group by ReservationMAC               
            having count(*) > 1) dt 
ON a.ReservationMAC=dt.ReservationMAC

使用cnt别名，您现在可以访问外部查询的SELECT子句中的重复项数。

Answer 2

使用JOIN，您可以获得所需的结果，如下所示：

SELECT Server, Network, ReservationIP, s.ReservationMAC, ReservationName
FROM ScopeReservations s
JOIN (
  SELECT ReservationMAC 
  FROM DHCP_ScopeReservations
  GROUP BY ReservationMAC
  HAVING COUNT(ReservationMAC) > 1
) dupe
ON s.ReservationMAC = dupe.ReservationMAC

内连接使用相同的表

2 个答案: