Question

有一个包含重复数据的表格，我可以使用此查询对电子邮件进行分组

SELECT id, first_name, email, status FROM customers WHERE status = '0' GROUP BY email

但是，我不想选择已经拥有状态=＆＃39; 1＆＃39;

的重复电子邮件的客户

表格设计如下......

id   first_name  email              status
1    Tony        tony@gmail.com       0
2    Terry       terry@gmail.com      0
3    Alex        alex@gmail.com       0
4    John        john@gmail.com       0
5    Mike        mike@gmail.com       1
6    Mike Jones  mike@gmail.com       0
7    Mike Fake   mike@gmail.com       0

我的查询仍然选择mike@gmail.com，因为状态为0，但实际上已经有状态= 1 ....我怎么不选择已经拥有状态的电子邮件= 1？

Answer 1

试试这个：

使用 LEFT JOIN

SELECT c.id, c.first_name, c.email, c.status 
FROM customers c 
LEFT OUTER JOIN customers c1 ON c.email = c1.email AND c1.cstatus = 1
WHERE c.status = 0 AND c1.id IS NULL
GROUP BY c.email;

使用 NOT EXISTS

SELECT c.id, c.first_name, c.email, c.status 
FROM customers c 
WHERE c.status = 0 AND 
      NOT EXISTS (SELECT 1 FROM customers c1 WHERE c.email = c1.email AND c1.cstatus = 1)
GROUP BY c.email;

Answer 2

最简单的方法是使用not exists

select c.* from customers c where not exists
(
  select 1 from customers c1
  where c1.email = c.email
  and c1.status = 1 
)

Answer 3

SELECT id, first_name, email, status, 
COUNT(CASE WHEN status = '0' THEN 1 END) AS zero_status_count
COUNT(CASE WHEN status = '1' THEN 1 END) AS one_status_count
FROM customers GROUP BY email having zero_status_count > 0 and one_status_count < 1;

试试这个。

MySQL：当其中一个状态= 1时，不要选择重复的行项

3 个答案: