Question

我有一个更新表记录的查询。

    UPDATE #TEMP
    SET [fld_LastName] = CustomerProfile.fld_LastName
    ,fld_FirstName = CustomerProfile.fld_FirstName
    ,fld_BirthDate = CustomerProfile.fld_BirthDate

FROM [DB_1].[dbo].[tbl_Customer] AS CustomerProfile --c
WHERE CustomerProfile.fld_CustomerNo = #TEMP.fld_CustomerNo

我想在客户不在的时候更新记录：

[DB_1].[dbo].[tbl_Customer]

我想要注意：

[DB_2].[dbo].[tbl_Customer]

我如何在SQL查询中执行此操作？

非常感谢。

Answer 1

这应该适合你：

UPDATE B
SET [fld_LastName] = CustomerProfile.fld_LastName
,fld_FirstName = CustomerProfile.fld_FirstName
,fld_BirthDate = CustomerProfile.fld_BirthDate
FROM [DB_1].[dbo].[tbl_Customer] AS CustomerProfile INNER JOIN #TEMP B
ON CustomerProfile.fld_CustomerNo = B.fld_CustomerNo
WHERE B.[fld_LastName] IS NULL OR B.fld_FirstName IS NULL OR B.fld_BirthDate IS NULL

Answer 2

您可以通过一次更新来完成。像这样：

 DECLARE @a TABLE (id INT, val INT)
 DECLARE @b TABLE (id INT, val INT)
 DECLARE @c TABLE (id INT, val INT)

 INSERT @a SELECT 1,NULL UNION SELECT 2,NULL UNION SELECT 3,30
 INSERT @b SELECT 1,10 
 INSERT @c SELECT 1,20 UNION SELECT 2,20 

 SELECT * FROM @a

 UPDATE @a 
    SET val = COALESCE(b.val,c.val,a.val)
   FROM @a a
        LEFT JOIN
        @b b ON a.id=b.id
        LEFT JOIN
        @c c ON a.id=c.id

 SELECT * FROM @a

这假设您更喜欢DB_1中从DB_2到NULL值的NOT NULL值 - 如果这些字段甚至可以为空。

UPDATE #TEMP
   SET fld_LastName = COALESCE(b.fld_LastName,c.fld_LastName,a.fld_LastName)
      ,fld_FirstName = COALESCE(b.fld_FirstName,c.fld_FirstName,a.fld_FirstName)
      ,fld_BirthDate = COALESCE(b.fld_BirthDate,c.fld_BirthDate,a.fld_BirthDate) 
 FROM #Temp a
         LEFT JOIN
         DB_1.dbo.tbl_Customer b ON a.fld_CustomerNo = b.fld_CustomerNo
         LEFT JOIN
         DB_2.dbo.tbl_Customer c ON a.fld_CustomerNo = c.fld_CustomerNo

查询以更新来自两个不同表的记录

2 个答案: