sqlzoo题解(by orzzzzzz)

最近在学习mysql，感觉sqlzoo的题目质量还挺好的（大部分，少部分有问题比如排序方式题意不清要求缺失xxxx），本身网址也是免费挺良心的，故开个题解博客，希望能进行学习与交流。

对应题解网址

• SELECT basics SELECT name SELECT from World: https://blog.csdn.net/aiqiyizz/article/details/109071276
• SELECT from Nobel: https://blog.csdn.net/aiqiyizz/article/details/109079108
• SELECT within SELECT: https://blog.csdn.net/aiqiyizz/article/details/109082291
• SUM and COUNT: https://blog.csdn.net/aiqiyizz/article/details/109083614
• JOIN: https://blog.csdn.net/aiqiyizz/article/details/109086001
• More JOIN operations: https://blog.csdn.net/aiqiyizz/article/details/109057783
• Using Null: https://blog.csdn.net/aiqiyizz/article/details/109062327
• Self join: https://blog.csdn.net/aiqiyizz/article/details/109064583