MySQL等 SQL语句在线练习

1. https://sqlzoo.net/wiki/SELECT_basics/zh
2. SQL语句在线练习 http://sample.jimstone.com.cn/xsql/
3. SQL语句测验 http://www.w3school.com.cn/quiz/quiz.asp?quiz=sql
4. sql语句练习50题(Mysql版)  https://blog.csdn.net/fashion2014/article/details/78826299/
5. http://sqlfiddle.com/