MERGE INTO USING ON WHEN matched / not matched then update / insert 用法——匹配上用update，匹配不上用insert
MERGE INTO USING用法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 execut
