有关mysql的utf8和utf8mb4，以及Illegal mix of collations for operation 'like'

参考以下几个帖子：

https://www.cnblogs.com/install/p/4417527.html

https://blog.csdn.net/Yetmoon/article/details/79941866

https://www.jb51.net/article/91638.htm

https://blog.csdn.net/u010584271/article/details/80835547

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最后这条管用，上面的也算了解一下

https://blog.csdn.net/qq_26245325/article/details/79157918

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