Merge语法：
1 MERGE INTO target [[AS] target-alias ] 2 USING source [[AS] source-alias ] 3 ON join-condition 4 WHEN MATCHED THEN UPDATE SET colname = value [, colname = value ...] 5 WHEN NOT MATCHED THEN INSERT [( <columns> )] VALUES ( <values> )
例子A：
1 MERGE INTO books b 2 USING purchases p 3 ON p.title = b.title and p.type = 'bk' 4 WHEN MATCHED THEN 5 UPDATE SET b.desc = b.desc || '; ' || p.desc 6 WHEN NOT MATCHED THEN 7 INSERT (title, desc, bought) values (p.title, p.desc, p.bought)
例子B：
1 MERGE INTO customers c 2 USING (SELECT * from customers_delta WHERE id > 10) cd 3 ON (c.id = cd.id) 4 WHEN MATCHED THEN 5 UPDATE SET name = cd.name 6 WHEN NOT MATCHED THEN 7 INSERT (id, name) values (cd.id, cd.name)
Mysql的语法：注意只能用inner join。
1 Update A inner join B on A.xx = B.xx 2 Set A.xxx = B.xxx