Sql 具有可传递数据的更新查询中的自联接

我在下表中列出了员工及其同事的数据，如果有匹配的同事和其他员工，我想更新员工表中的bucketid

在这个例子中

Employee=101与Employee=103同事（即c1）匹配，因此两者的bucketid=1（即两个bucketid的最小值）

Employee=102与Employee=103同事（即c3）匹配，因此两者应具有相同的bucketid，但此处应使用1更新，因为Employee=102 bucketid刚刚更改为1。在这个例子中，我们有可传递的依赖于法律的数据

(i.e. a=b and b=c then a=c)

员工表：

EmployeeID  EmployeeName    BucketID
101         williams        1
102         williams        2
103         williams        3
104         williams        4

员工/同事表：

EmployeeID  Colleague
101         c1
101         c2
102         c3
102         c4
103         c1
103         c3
104         c7

我尝试使用这个更新查询

 update a2
 set BucketID = a1.BucketID
 from Employee a1
 inner join Emp_Colleagues c1 on a1.EmployeeID=c1.EmployeeID 
 inner join Employee a2 on a1.EmployeeName=a2.EmployeeName
 inner join Emp_Colleagues c2 on a2.EmployeeID=c2.EmployeeID
 where c1.Colleague=c2.Colleague and a1.BucketID <> a2.BucketID

但我希望在Employee表中输出如下

EmployeeID  EmployeeName    BucketID
101         williams        1
102         williams        1
103         williams        1
104         williams        4

---

我不认为你能在一个更新语句中做到这一点。但是，您可以使用循环不断更新，直到没有任何内容可更新：

declare @updates int = 1
while @updates > 0
begin
    update a2
        set BucketID = a1.BucketID
        from Employee a1
        inner join Emp_Colleagues c1 on a1.EmployeeID=c1.EmployeeID
        inner join Emp_Colleagues c2 on c1.Colleague=c2.Colleague
        inner join Employee a2 on a2.EmployeeID=c2.EmployeeID
        where a1.BucketID < a2.BucketID
    set @updates = @@ROWCOUNT
end

declare@updates int=1
而@updates>0
开始
更新a2
设置BucketID=a1.BucketID
来自员工a1
内部连接a1上的Emp_同事c1。EmployeeID=c1.EmployeeID
内部连接Emp_同事c1上的c2。同事=c2。同事
内部连接a2上的员工a2。EmployeeID=c2。EmployeeID
其中a1.BucketID

这是您要查找的查询

with CTE as
(
select EmployeeID as E1, EmployeeID as E2, cast('\' as varchar(MAX)) as list
from Employee
Union all
select E1, T2_2.EmployeeID, CTE.list +  CAST(E1 as varchar(MAX)) + '-' + CAST(T2_2.EmployeeID as varchar(MAX)) + '\'
from CTE
    inner join Employee_Colleague T2_1 ON CTE.E2 = T2_1.EmployeeID
    inner join Employee_Colleague T2_2 ON T2_1.Colleague = T2_2.Colleague
where CTE.list not like '%\' + CAST(E1 as varchar(MAX)) + '-' + CAST(T2_2.EmployeeID as varchar(MAX)) + '\' +'%'
)

Update T1_1
Set T1_1.BucketID = (select MIN(T1_2.BucketID) 
                        from Employee T1_2 
                            inner join CTE ON T1_1.EmployeeID = CTE.E1 AND T1_2.EmployeeID = CTE.E2
                    )
from Employee T1_1 

---

您尝试的查询有什么问题？它返回的是上面提到的输出，而不是我实际想要的。您需要一个递归CTE来执行此操作，因为可能存在不确定数量的转换，例如

a=b和b=c和c=d

，然后

a=d

。是的，您可以使用递归CTE编写查询@Giorgosbetosi认为我们可以通过使用递归CTE来实现这一点。。你知道吗？上面的表格中有大量的数据。我运行了这个查询，但从2天开始就无法执行。上面的查询解决了我的问题。你能帮助我使用递归查询吗。谢谢。：-）

with CTE as
(
select EmployeeID as E1, EmployeeID as E2, cast('\' as varchar(MAX)) as list
from Employee
Union all
select E1, T2_2.EmployeeID, CTE.list +  CAST(E1 as varchar(MAX)) + '-' + CAST(T2_2.EmployeeID as varchar(MAX)) + '\'
from CTE
    inner join Employee_Colleague T2_1 ON CTE.E2 = T2_1.EmployeeID
    inner join Employee_Colleague T2_2 ON T2_1.Colleague = T2_2.Colleague
where CTE.list not like '%\' + CAST(E1 as varchar(MAX)) + '-' + CAST(T2_2.EmployeeID as varchar(MAX)) + '\' +'%'
)

Update T1_1
Set T1_1.BucketID = (select MIN(T1_2.BucketID) 
                        from Employee T1_2 
                            inner join CTE ON T1_1.EmployeeID = CTE.E1 AND T1_2.EmployeeID = CTE.E2
                    )
from Employee T1_1