Sql server 2005 如果sql server 2005中的原始表中不存在，则从一个表更新到另一个表

我有两个具有相同列的表-T1，T2。我想根据键列从T2中存在的列更新表T1列：如果键列存在，则从T2更新T1的其余列；如果不存在，则将整行从T2插入T1

此查询不起作用：

IF EXISTS (SELECT keyC FROM T2 WHERE keyC in (select keyC from T1)) 
UPDATE T1 SET T1.c1 = T2.c1,
T1.c2 = T2.c2,
from  T2 WHERE  T2.keyC in (select keyC from T1)
ELSE (INSERT INTO T1 select * from T2)

知道怎么修吗

提前感谢,

---

Greg

对于SQL Server 2008，请看一下使用该语句

MERGE T1 AS target
USING T2 AS source
ON (target.keyC = source.keyC)
WHEN MATCHED THEN 
    UPDATE SET c1 = source.c1, c2 = source.c2
WHEN NOT MATCHED THEN   
    INSERT (keyC, c1, c2)
    VALUES (source.keyC, source.c1, source.c2)

编辑：OP将问题从2008年更改为2005年

对于早期版本，您需要2个操作：

UPDATE target
    SET c1 = source.c1, c2 = source.c2
    FROM T1 AS target
        INNER JOIN T2 as source
            ON target.keyC = source.keyC

INSERT INTO T1
    (keyC, c1, c2)
    SELECT keyC, c1, c2
        FROM T2
        WHERE NOT EXISTS(SELECT NULL FROM T1 WHERE keyC = T2.keyC)

---

在SQL2008中，可以使用优雅的合并语句：

MERGE T1 AS target
USING T2 AS source ON (target.KeyC = source.KeyC)
WHEN MATCHED THEN 
    UPDATE SET  c1 = source.c1,
                c2 = source.c2
WHEN NOT MATCHED THEN   
    INSERT (c1, c2)
    VALUES (source.c1, source.c2);

---

因为您使用的是SQLServer2005，所以不能使用merge，必须执行两条语句。一次更新和一次插入

declare @T1 table (keyC int, c1 int)
declare @T2 table (keyC int, c1 int)

insert into @T1 values (1, 1)

insert into @T2 values (1, 10)
insert into @T2 values (2, 20)

-- Update all rows
update @T1 set
  c1 = T2.c1
from @T1 as T1
  inner join @T2 as T2
    on T1.keyC = T2.keyC

-- Insert new rows
insert into @T1 (keyC, c1)
select keyC, c1
from @T2 as T2
where not exists (select *
                  from @T1 as T1
                  where T1.keyC = T2.keyC)

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由于不能在一条语句中执行，是否需要将其作为一条语句执行