MySQL学习记录(三)

数据导入导出

报错记录

• ERROR 1290 (HY000): The MySQL server is running with the --secure-file-priv option so it cannot execute this statement
  参考教程：

1. https://blog.youkuaiyun.com/u011677147/article/details/64129606
2. secure_file_priv = NULL
   https://blog.youkuaiyun.com/weixin_39631030/article/details/79873936
   https://blog.youkuaiyun.com/qq_35246620/article/details/78148505

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练习一：各部门工资最高的员工

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练习二: 换座位

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练习三: 分数排名

#使用函数
SELECT score, 
       DENSE_RANK() OVER(ORDER BY score DESC) AS 'Rank'
FROM scores;

#Rank 不带引号 会报错 
SELECT score,
      (SELECT count(DISTINCT score) 
       FROM scores AS b 
       WHERE b.Score >= a.Score) 'Rank'
FROM scores AS a
ORDER BY score DESC;

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练习四：连续出现的数字

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练习五：树节点

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练习六：至少有五名直接下属的经理

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