怎么把一个表的值用update更新到另一个表中

[tanshihou]

现在有两个表t1和t2分别是
a b c
------------------
11 21
12 22
13 23

a c
------------------
11 31
12 32
13 33

想把t2表的c字段用update语句更新到t1中，想得到的结果

a b c
------------------
11 21 31
12 22 32
13 23 33

只想用update，不想再定义一个表变量然后insert，这样会浪费空间

[發糞塗牆]

UPDATE t1 SET t1.c=t2.c FROM t1 INNER JOIN t2 ON t1.a=t2.a

[小魚人]

create table #t1(a varchar(5), b varchar(5),c varchar(5)) 
insert into #t1 select '11', '21',null union all select '12', '22',null union all select '13','23',null 

create table #t2(a varchar(5), c varchar(5))
 insert into #t2 select '11', '31' 
 union all select '12', '32'
 union all select '13', '33'

 
 select * from #t1
 select * from #t2
 
 UPDATE #t1
 SET #t1.c=#t2.c
 FROM #t1 INNER JOIN #t2 ON #t1.a=#t2.a 
 
 select * from #t1
 select * from #t2
   
  drop table #t1
  drop table #t2