mysql中常见的sql语句语法书写操作

参见：https://blog.csdn.net/weixin_39904587/article/details/110864443

https://www.cnblogs.com/wumingoo1/p/14034695.html

https://www.cnblogs.com/yang1182/p/9613988.html

https://www.cnblogs.com/coder-wf/p/11128033.html

https://www.cnblogs.com/zsty/p/10109125.html