以下为测试例子。 1.首先创建两张临时表并录入测试数据： 复制代码 代码如下: create table #temptest1 ( id int, name1 varchar(50), age int ) create table #temptest2 ( id int, name1 varchar(50), age int ) 查询出此
以下为测试例子。 1.首先创建两张临时表并录入测试数据： 复制代码 代码如下: create table #temptest1 ( id int, name1 varchar(50), age int ) create table #temptest2 ( id int, name1 varchar(50), age int )
查询出此时的表数据为：
#temptest1 #temptest2
2.现在要将#temptest2中的年龄更新到相应的#temptest1中的年龄。
其实就是让[表1]中ID为1的年龄改成19，同时ID为2的年龄改成20。
当然这里的要求是只用一句SQL，不能用循环。
结果如下：
实现方法如下：
Update t1
Set t1 .age = t2.age
From #temptest1 t1
Join #temptest2 t2
On t1.id = t2.id
(补充)Sql Server 2008 Merge命令写法：
merge into #temptest1 t1 using(select age,id from #temptest2) t2on t1.id = t2.idwhen matched thenupdate set t1.age = t2.age
是不是挺有趣的Sql。如何一次性更新多条不同值的记录标题可能没说清楚，假设有这样两张表： 复制代码 代码如下: create table testA( id number, eng varchar2(3), chi varchar2(3) ) create table testB( id number, eng varchar2(3), chi varchar2(3)， anythingother varchar2(1) ) 现有记录 testA： ID ENG CHI =============== 1 a 一 2 b 二 3 c 三 testB: ID ENG CHI ANY.... ================= 1 d 四 2 e 五 3 f 六 我想把testB中的记录的ENG,CHI字段更新到testA中去，以ID来对应。 CODE: SQL> set autot on SQL> update ta set ta.b=(select tb.b from tb where ta.a=tb.a) where exists (select 1 from tb where ta.a=tb.a); 已更新4行。 已用时间: 00: 00: 00.01 执行计划 ---------------------------------------------------------- Plan hash value: 1137212925 -------------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | -------------------------------------------------------------------------------- | 0 | UPDATE STATEMENT | | 5 | 165 | 20 (30)| 00:00:01 | | 1 | UPDATE | TA | | | | | |* 2 | HASH JOIN SEMI | | 5 | 165 | 5 (20)| 00:00:01 | | 3 | TABLE ACCESS FULL | TA | 5 | 100 | 2 (0)| 00:00:01 | | 4 | VIEW | VW_SQ_1 | 4 | 52 | 2 (0)| 00:00:01 | | 5 | TABLE ACCESS FULL| TB | 4 | 52 | 2 (0)| 00:00:01 | |* 6 | TABLE ACCESS FULL | TB | 1 | 26 | 2 (0)| 00:00:01 | -------------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 2 - access("TA"."A"="ITEM_1") 6 - filter("TB"."A"=:B1) Note ----- - dynamic sampling used for this statement (level=2) 统计信息 ---------------------------------------------------------- 0 recursive calls 4 db block gets 23 consistent gets 0 physical reads 1004 redo size 840 bytes sent via SQL*Net to client 856 bytes received via SQL*Net from client 3 SQL*Net roundtrips to/from client 1 sorts (memory) 0 sorts (disk) 4 rows processed SQL> update ta set ta.b=(select tb.b from tb where ta.a=tb.a) where ta.a= (select tb.a from tb where ta.a=tb.a); 已更新4行。 已用时间: 00: 00: 00.00 执行计划 ---------------------------------------------------------- Plan hash value: 3571861550 ---------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | ---------------------------------------------------------------------------- | 0 | UPDATE STATEMENT | | 1 | 20 | 7 (15)| 00:00:01 | | 1 | UPDATE | TA | | | | | |* 2 | FILTER | | | | | | | 3 | TABLE ACCESS FULL| TA | 5 | 100 | 2 (0)| 00:00:01 | |* 4 | TABLE ACCESS FULL| TB | 1 | 13 | 2 (0)| 00:00:01 | |* 5 | TABLE ACCESS FULL | TB | 1 | 26 | 2 (0)| 00:00:01 | ---------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 2 - filter("TA"."A"= (SELECT "TB"."A" FROM "TB" "TB" WHERE "TB"."A"=:B1)) 4 - filter("TB"."A"=:B1) 5 - filter("TB"."A"=:B1) Note ----- - dynamic sampling used for this statement (level=2) 统计信息 ---------------------------------------------------------- 11 recursive calls 1 db block gets 53 consistent gets 0 physical reads 588 redo size 840 bytes sent via SQL*Net to client 858 bytes received via SQL*Net from client 3 SQL*Net roundtrips to/from client 1 sorts (memory) 0 sorts (disk) 4 rows processed 如果 create unique index tb_a_uidx on tb(a); [Copy to clipboard] [ - ] CODE: SQL> update (select ta.b tab1 ,tb.b tbb from ta,tb where ta.a=tb.a) set tab1=tbb; 已更新4行。 已用时间: 00: 00: 00.01 执行计划 ---------------------------------------------------------- Plan hash value: 1761655026 ---------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | ---------------------------------------------------------------------------- | 0 | UPDATE STATEMENT | | 4 | 184 | 5 (20)| 00:00:01 | | 1 | UPDATE | TA | | | | | |* 2 | HASH JOIN | | 4 | 184 | 5 (20)| 00:00:01 | | 3 | TABLE ACCESS FULL| TB | 4 | 104 | 2 (0)| 00:00:01 | | 4 | TABLE ACCESS FULL| TA | 5 | 100 | 2 (0)| 00:00:01 | ---------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 2 - access("TA"."A"="TB"."A") Note ----- - dynamic sampling used for this statement (level=2) 统计信息 ---------------------------------------------------------- 8 recursive calls 4 db block gets 17 consistent gets 0 physical reads 1004 redo size 840 bytes sent via SQL*Net to client 827 bytes received via SQL*Net from client 3 SQL*Net roundtrips to/from client 3 sorts (memory) 0 sorts (disk) 4 rows processed
