SQL将一列插入另一个匹配的表

Question

I have two tables a and b.

a:

TYPE            nvarchar(MAX)   
USERID          nvarchar(MAX)   
FIRSTNAME       nvarchar(MAX)   
LASTNAME        nvarchar(MAX)   
USERSTATUS      nvarchar(MAX)   
EMPLOYEETYPE    nvarchar(MAX)   
MANAGERID       nvarchar(MAX)   
STATUS          nvarchar(MAX)   
WEEKNUM         nvarchar(MAX)   
POLICYNAME      nvarchar(MAX)   
Acc_Check       nvarchar(MAX)   

b:

TYPE            nvarchar(MAX)   
USERID          nvarchar(MAX)   
FIRSTNAME       nvarchar(MAX)   
LASTNAME        nvarchar(MAX)   
USERSTATUS      nvarchar(MAX)   
EMPLOYEETYPE    nvarchar(MAX)   
MANAGERID       nvarchar(MAX)   
STATUS          nvarchar(MAX)   
WEEKNUM         nvarchar(MAX)   
Acc_Check       nvarchar(MAX)   
Policy_Name     nvarchar(MAX)   

Table b is created by using SELECT DISTINCT on table a without POLICYNAME.

I now need to add the correct policyname back in to the new table.

Where Acc_Check is equal in both tables I want to take the matching value of a.POLICYNAME and insert it into b.Policy_Name

Answer 1

You just have to join these tables

UPDATE b
SET b.Policy_Name  = a.POLICYNAME      
FROM b INNER JOIN a
ON b.Acc_Check = a.Acc_Check