1、复制表（包括表结构、表数据）
SqlServer：
Select * into user_copy from user
MySql：
CREATE TABLE user_copy LIKE user;
INSERT INTO user_copy SELECT * FROM user;
2、多表连接做update
SqlServer：
UPDATE s1 SET s1.salary= s2.salary
FROM (SELECT * FROM s WHERE age>10) AS s1 JOIN s2 ON s1.uname= s2.uname
WHERE s1.uname = 'xx'
MySql：(无法直接对目标表的查询数据直接做更新，只能针对目标表操作)
UPDATE s1 JOIN s2 ON s1.uname= s2.uname
SET s1.salary= s2.salary
WHERE s1.uname = 'xx'