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Oracle9i中MERGE的用法

程序员文章站 2022-05-06 12:09:06
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语法: MERGE [hint] INTO [schema .] table [t_alias] USING [schema .] { table | view | subquery } [t_alias] ON ( condition ) WHEN MATCHED THEN merge_update_clause WHEN NOT MATCHED THEN merge_insert_clause; ORACLE 9I中加入了MERGE 语法: MERG

  语法:

  MERGE [hint] INTO [schema .] table [t_alias] USING [schema .] { table | view | subquery } [t_alias] ON ( condition ) WHEN MATCHED THEN merge_update_clause WHEN NOT MATCHED THEN merge_insert_clause;

  ORACLE 9I中加入了MERGE

  语法:

  MERGE [hint] INTO [schema .] table [t_alias] USING [schema .] { table | view | subquery } [t_alias] ON ( condition ) WHEN MATCHED THEN merge_update_clause WHEN NOT MATCHED THEN merge_insert_clause;

  构建测试数据表

  create table tj_test

  (id number,

  name varchar2(20),

  age number)

  向表中插入数据

  insert into tj_test

  values

  (1,'jan',23)

  insert into tj_test

  values

  (2,'kk',22)

  insert into tj_test

  values

  (3,'joe',27)

  select * from tj_test

  1 jan 23

  2 kk 22

  3 joe 27

  构建另一新表

  create table tj_test1 as select * from tj_test where 1=0

  插入一笔数据

  insert into tj_test1

  values

  (1,'jlk',23)

  select * from tj_test1

  1 jkl 23 --注意,,这里的NAME字段中的值是jkl

  使用MERGE,实现有则更新,无则插入

  merge into tj_test1 tt1

  using tj_test tt

  on (tt1.id=tt.id)

  when matched then

  update set

  tt1.name=tt.name,

  tt1.age=tt.age

  when not matched then

  insert values(

  tt.id,

  tt.name,

  tt.age)

  查询tj_test1表(对比原来表中的数据,更新了ID=1 ROW中字段NAME同时,多出两笔新数据)

  select * from tj_test1

  1 jan 23 --这里的原有jkl值被更新

  3 joe 27 --原来表中没有的插入

  2 kk 22 --原来表中没有的插入