SQL语句

1、将一个表中数据查出插入另一张表中

insert into user(username,password,role) select code,'111','teacher' from teacher

2、根据查询结果更新

UPDATE MyTable INNER JOIN  MyTable_Temp  

ON MyTable.ID=MyTable_Temp.ID  

SET MyTable.Col1=MyTable_Temp.Col1, MyTable.Col2=MyTable_Temp.Col2.....

3、将一个表中数据查询出添加到另一张表中

INSERT INTO clazz(code, stucount) SELECT DISTINCT clazz AS code,COUNT(*) AS stucount FROM student GROUP BY student.clazz