merge into 解决用B表跟新A表数据，如果A表中没有，则把B表的数据插入A表；

语法：

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 execute some update sql or something else ]

WHEN NOT MATHED THEN [execute something else here ! ]

 

Merge Into emp_bak  i

Using ( Select emp_no,Name,salary,bonus From emp)  s

On (i.emp_no=s.emp_no)

When Matched Then

 Update  Set i.salary=s.salary,i.bonus=s.bonus

 When Not Matched Then

 Insert (i.emp_no,i.Name,i.salary,i.bonus) Values(s.emp_no,s.Name,s.salary,s.bonus);

 

如果数据量很大，此sql效率非常高