Oracle merge into 学习

用途

将A表的数据输出到B表中，根据条件判断B表中是否有数据，有则更新，没有则插入

语法

merge into table1 alias1 using table2 alias2 on (condition) when matched then update set col1=col2 when not matched then insert (col1) values (col2)

示例

MERGE INTO SCOTT.TEST_USERS m0 USING ( SELECT t0.USERID, t0.USERNAME FROM SCOTT.USERS ) m1 ON (m0.USERID = m1.USERID) WHEN MATCHED THEN UPDATE SET USERNAME = m1.USERNAME WHEN NOT MATCHED THEN INSERT (USERID, USERNAME) VALUES (m1.USERID, m1.USERNAME)