Question

这是我的表格的简化版本

Name      Vlan
Switch 1    1
Switch 1    2
Switch 1    3
Switch 2    1
Switch 2    2

我想将属于交换机1的所有vlan与属于交换机2的所有vlan进行比较，并使用SQL查询在其中一个交换机中打印出丢失的vlans。有可能这样做吗？请注意，所有数据都位于同一个表中。

在上面提供的示例数据中，查询应该返回第3行

Switch 1,  3

以下是我之前尝试的查询（我的要求比我的查询中的简化版本更多的条件）：

Select Vlans.VLANID From VLANS
 JOIN Nodes ON 
VLANS.NodeId = Nodes.NodeID
Where Nodes.sysName LIKE 'SSW010%' and Vlans.VlanID NOT In
(Select Vlans.VLANID AS Vlan2 From VLANS
 JOIN Nodes ON 
VLANS.NodeId = Nodes.NodeID
Where Nodes.sysName LIKE 'SSW001%')

Answer 1

这将为您提供您所追求的目标。它没有对数据做出任何假设，并会给出所有缺失的记录。如果您想将其限制为仅限于“切换1”和“切换1”。然后将其添加到WHERE子句中。

SELECT
  t1.Name,
  t1.Vlan
FROM t t1
WHERE NOT EXISTS (SELECT 1 
                    FROM t t2
                   WHERE t2.Name <> t1.Name
                     AND t2.Vlan = t1.Vlan)

CREATE TABLE t 
(
  Name VARCHAR(10),
  Vlan INT
)


INSERT INTO t VALUES('Switch 1',1)   
INSERT INTO t VALUES('Switch 1', 2)
INSERT INTO t VALUES('Switch 1', 3)
INSERT INTO t VALUES('Switch 2', 1)
INSERT INTO t VALUES('Switch 2', 2)

Answer 2

使用MS SQL Server。在 SQL Fiddle

上查看此工作代码

SELECT T1.Name, T1.Vlan
  FROM yourTable T1
 WHERE NOT EXISTS (SELECT 1 
                     FROM yourTable T2
                    WHERE T2.Vlan = T1.Vlan
                      AND T2.Name <> T1.Name)

Answer 3

这应该有用。

select 
  t1.Name
  ,t1.Vlan
from table t1
left join table t2 
  on t1.Vlan = t2.Vlan 
 and t1.Name='Switch 1' 
 and t2.Name = 'Switch 2'
where  t2.Name is null
union
select 
  t1.Name
  ,t1.Vlan
from table t1
left join table t2 
  on t1.Vlan = t2.Vlan 
 and t1.Name='Switch 2' 
 and t2.Name = 'Switch 1'
where  t2.Name is null

Answer 4

SELECT * 
FROM yourTable 
WHERE [Name] = 'Switch1'
AND [Vlan] NOT IN(SELECT [Vlan] FROM yourTable WHERE [Name] = 'Switch2')


Name    Vlan
Switch1 3

如何比较同一个表中的记录并查找丢失的记录

4 个答案: