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Customers Who Never Order

Customers Who Never Order

作者: myang199088 | 来源:发表于2015-04-16 08:36 被阅读20次
    • Problem
      Suppose that a website contains two tables, the Customers table and the Orders table. Write a SQL query to find all customers who never order anything.
      Table: Customers.
      +----+-------+
      | Id | Name |
      +----+-------+
      | 1 | Joe |
      | 2 | Henry |
      | 3 | Sam |
      | 4 | Max |
      +----+-------+
      Table: Orders.
      +----+------------+
      | Id | CustomerId |
      +----+------------+
      | 1 | 3 |
      | 2 | 1 |
      +----+------------+
      Using the above tables as example, return the following:
      +-----------+
      | Customers |
      +-----------+
      | Henry |
      | Max |
      +-----------+

    • Code

    Write your MySQL query statement below

    select Name from Customers where Id not in (select * from(select CustomerId from Orders) t)

    select c.Name from Customers c left join Orders o on c.id = o.CustomerId where o.CustomerId is NULL

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