SQL Server 用一張表的數據更新另外一張表的數據（轉載）

 

文章一：SQL Server中如何基於一個表的數據更新另外一個表的對應數據的SQL語句腳本

https://codedefault.com/2017/sql-server-update-from-a-select

方式一 INNER JOIN

UPDATE Table_A SET Table_A.col1 = Table_B.col1, Table_A.col2 = Table_B.col2 FROM Some_Table AS Table_A INNER JOIN Other_Table AS Table_B ON Table_A.id = Table_B.id WHERE Table_A.col3 = 'cool' 

方式二 使用MERGE關鍵字

MERGE INTO YourTable T USING other_table S ON T.id = S.id AND S.tsql = 'cool' WHEN MATCHED THEN UPDATE SET col1 = S.col1, col2 = S.col2; 

或者

MERGE INTO YourTable T USING ( SELECT id, col1, col2 FROM other_table WHERE tsql = 'cool' ) S ON T.id = S.id WHEN MATCHED THEN UPDATE SET col1 = S.col1, col2 = S.col2; 

注： SQL Server 2008 或者以上版本才支持MERGE關鍵字

方式三 使用CTE

;WITH CTE
     AS (SELECT T1.Col1, T2.Col1 AS _Col1, T1.Col2, T2.Col2 AS _Col2 FROM T1 JOIN T2 ON T1.id = T2.id /*Where clause added to exclude rows that are the same in both tables Handles NULL values correctly*/ WHERE EXISTS(SELECT T1.Col1, T1.Col2 EXCEPT SELECT T2.Col1, T2.Col2)) UPDATE CTE SET Col1 = _Col1, Col2 = _Col2 

方式四 使用EXISTS

UPDATE suppliers SET supplier_name = (SELECT customers.name FROM customers WHERE customers.customer_id = suppliers.supplier_id) WHERE EXISTS (SELECT customers.name FROM customers WHERE customers.customer_id = suppliers.supplier_id);

文章二：SQL 用一個表的數據更新另外一張表

https://blog.51cto.com/alun51cto/2392062?source=dra

用表B的數據（B1列,B2）更新表A的A1,A2列

SQL Server:

update A SET A.A1 = b.B1,A.A2=B.A2 FROM A ,B WHERE A.ID1 = B.ID1 and A.ID2 = B.ID2;

Access:

update A, B set A.A1 = B.B1,A.A2=B.B2 where A.ID1 = B.ID1 and A.ID2 = B.ID2; --或 update A INNER JOIN B ON A.ID1 = B.ID1 AND A.ID2= B.ID2 SET A.A1 = B.B1,A.A2=B.B2;

經過一條ＳＱＬ語句一次更新多條數據．ＳＱＬ語句寫法略有不一樣，以下：

方法一:

Update T1 set dc=(select dc1 from t2 where T1.A=T2.A1 AND T1.B=T2.B1) WHERE T1.AID in ( SELECT AID FROM T1 INNER JOIN T2 ON t1.A=T2.A1 AND T1.B=T2.B1 )

注：在我標我紅色的in地方若是把'in'換成'='將出錯，但在下面的Ｂ種寫法裏就能夠換成'=',變成Ｃ方法寫法.

方法二：

Update T1 set dc=(select dc1 from t2 where T1.A=T2.A1 AND T1.B=T2.B1) WHERE T1.AID in ( SELECT T1.AID FROM T2 WHERE t1.A=T2.A1 AND T1.B=T2.B1 )

方法三：

Update T1 set dc=(select dc1 from t2 where T1.A=T2.A1 AND T1.B=T2.B1) WHERE T1.AID = ( SELECT T1.AID FROM T2 WHERE t1.A=T2.A1 AND T1.B=T2.B1 )

方法四：

Update T1 set dc=(select dc1 from T2 where T1.A=T2.A1 AND T1.B=T2.B1) WHERE T1.A = ( SELECT T1.A FROM T2 WHERE T1.A=T2.A1 AND T1.B=T2.B1 )

方法五：

Update T1 set dc=(select dc1 from T2 where T1.A=T2.A1 AND T1.B=T2.B1) WHERE T1.A = ( SELECT T2.A1 FROM T2 WHERE T1.A=T2.A1 AND T1.B=T2.B1 )

方法六:　

Update T1 set dc=(select dc1 from T2 where T1.A=T2.A1 AND T1.B=T2.B1) WHERE T1.A in ( SELECT T2.A1 FROM T2 WHERE T1.A=T2.A1 AND T1.B=T2.B1 )

注：若是在上面方法改寫成以下的寫法將會出錯。

Update T1 set dc=(select dc1 from T2 where T1.A=T2.A1 AND T1.B=T2.B1) WHERE T1.A in ( SELECT T1.A FROM T1 INNER JOIN T2 ON t1.A=T2.A1 AND T1.B=T2.B1 )

此種方法將會更新掉全部符合T1.A in ()這個條件的數據,因此是不正確的, 因此不能這樣寫。

方法七：

Update T1 set dc=(select dc1 from T2 where T1.A=T2.A1 AND T1.B=T2.B1 AND T1.DC=T2.DC1) FROM T1, T2 WHERE T1.A=T2.A1 AND T1.B=T2.B1

方法八：

Update T1 set T1.dc=T2.dc1 FROM T1 INNER JOIN T2 ON T1.A=T2.A1 AND T1.B=T2.B1 WHERE t1.A=T2.A1 AND T1.B=T2.B1

方法九：

Update T1 set T1.dc=T2.dc1 FROM T1, T2 WHERE T1.A=T2.A1 AND T1.B=T2.B1

請特別注意以上方法中我用紅色標記上的代碼寫法。

總節：雖然是一條簡單的更新語名但也有多種寫法，且每種寫法各有優缺點。

你們是否還有更簡單的寫法或者更容易理解的寫法？若是有請提出來一塊兒討論，謝謝！

說明測試環境：以上代碼在ＭＳＳＱＬ2005中驗證是可行的．

　　注：此處我用灰色標記的部分能夠去掉。