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leetcode_sql_2

时间:2017-07-04 20:21:14      阅读:264      评论:0      收藏:0      [点我收藏+]

标签:null   etc   who   web   site   --   custom   nbsp   website   

183. Customers Who Never Order

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       |
+-----------+

  solutions:

SELECT A.Name from Customers A
LEFT JOIN Orders B on  a.Id = B.CustomerId
WHERE b.CustomerId is NULL

 

SELECT A.Name from Customers A
WHERE NOT EXISTS (SELECT 1 FROM Orders B WHERE A.Id = B.CustomerId)

SELECT A.Name from Customers A
WHERE A.Id NOT IN (SELECT B.CustomerId from Orders B)

select c.Name from Customers c
where (select count(*) from Orders o where o.customerId=c.id)=0

 

 

 

leetcode_sql_2

标签:null   etc   who   web   site   --   custom   nbsp   website   

原文地址:http://www.cnblogs.com/coskaka/p/7117805.html

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