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(LeetCode:数据库)从不订购的客户

(LeetCode:数据库)从不订购的客户

作者: lconcise | 来源:发表于2018-09-04 19:45 被阅读1次

    某网站包含两个表,Customers 表和 Orders 表。编写一个 SQL 查询,找出所有从不订购任何东西的客户。

    Customers

    +----+-------+
    | Id | Name  |
    +----+-------+
    | 1  | Joe   |
    | 2  | Henry |
    | 3  | Sam   |
    | 4  | Max   |
    +----+-------+
    

    Orders

    +----+------------+
    | Id | CustomerId |
    +----+------------+
    | 1  | 3          |
    | 2  | 1          |
    +----+------------+
    

    例如给定上述表格,你的查询应返回:

    +-----------+
    | Customers |
    +-----------+
    | Henry     |
    | Max       |
    +-----------+
    

    Solution

    SELECT
        c. NAME AS customers
    FROM
        customers c
    WHERE
        c.id NOT IN (
            SELECT
                a.id
            FROM
                customers a,
                orders b
            WHERE
                a.id = b.customerId
        );
    

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