語法：
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
語法：
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;
構建測試數據表
create table tj_test
(id number,
name varchar2(20),
age number)
向表中插入數據
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
構建另一新表
create table tj_test1 as select * from tj_test where 1=0
插入一筆數據
insert into tj_test1
values
(1,'jlk',23)
select * from tj_test1
1 jkl 23 --注重，這裡的NAME字段中的值是jkl
使用MERGE,實現有則更新，無則插入
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)
查詢tj_test1表(對比原來表中的數據，更新了ID＝1 ROW中字段NAME同時，多出兩筆新數據)
select * from tj_test1
1 jan 23 --這裡的原有jkl值被更新
3 joe 27 --原來表中沒有的插入
2 kk 22 --原來表中沒有的插入
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