MERGE INTO [your table-name] [rename your table here] USING ( [write your query here] )[rename your query-sql and using just like a table] ON ([conditional expression here] AND [...]...) WHEN MATHED THEN [here you can execute some update sql or something else ] WHEN NOT MATHED THEN [execute something else here ! ]
在一个同时存在Insert和Update语法的Merge语句中,总共Insert/Update的记录数,就是Using语句中的记录数。
例:当T表中如果存在a='1001' 的记录的话,就把b的值设为2,否则就Insert一条a='100',b=2的记录到T中:
MERGE INTO T T1 USING (SELECT '1001' AS a,2 AS b FROM dual) T2 ON ( T1.a=T2.a) WHEN MATCHED THEN UPDATE SET T1.b = T2.b WHEN NOT MATCHED THEN INSERT (a,b) VALUES(T2.a,T2.b);