mysql编码问题。

　　utf8mb4_general_ci与utf8mb4_0900_ai_ci

　　https://www.cnblogs.com/seasonhu/p/14994857.html

mysql - explain

　　https://gitee.com/gorm/gen#%E6%A0%B9%E6%8D%AE%E4%B8%BB%E9%94%AE%E6%9F%A5%E8%AF%A2%E6%95%B0%E6%8D%AE

gorm语法

　　https://gitee.com/gorm/gen#%E6%A0%B9%E6%8D%AE%E4%B8%BB%E9%94%AE%E6%9F%A5%E8%AF%A2%E6%95%B0%E6%8D%AE