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- LeetCode 系列笔记来源于 LeetCode 题库1,在个人思考的基础之上博采众长,受益匪浅;故今记此文,感怀于心,更多题解及程序,参见 Github2;
- 该系列笔记不以盈利为目的,仅用于个人学习、课后复习及交流讨论;
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1. LeetCode 181
- 考察点:内连接的三种方式;
WHERE
子句:SELECT-FROM
语句生成笛卡尔积,然后使用WHERE
子句筛选结果;INNER-JOIN-ON
:根据ON
子句中的条件执行内连接;NATURAL JOIN
:自然连接只能匹配两张表中的同名列,因此不适用于本题;
2. WHERE 子句
-- Approach 1: WHERE
SELECT
e.Name AS Employee
FROM
Employee AS e,
Employee AS m
WHERE
e.ManagerId = m.Id
AND e.Salary > m.Salary;
3. INNER-JOIN-ON
-- Approach 2: INNER JOIN
inner join
SELECT
Employee.Name AS Employee
FROM
Employee
JOIN
Employee M ON Employee.ManagerId = M.Id
WHERE
Employee.Salary > M.Salary;