MERGE INTO [target-table] A USING [source-table sql] B ON([conditional expression] and [...]...)
WHEN MATCHED THEN
[UPDATE sql]
WHEN NOT MATCHED THEN
[INSERT sql]
举例子:
MERGE INTO A t1
USING (select count(*) c from A t2 where t2.key='key1' )x
ON (x.c > 0)
when matched then
update set t1.value='test', t1.version = sysdate where t1.key='key1
when not matched then
insert values('值1','值2','值3');