Question

我有一个带有列的表：唯一ID，收件人，发送日期和状态。

当send_date> xx并且status ='something'时，我想为不同的收件人选择ID

我已经尝试过了：

SELECT * 
FROM EmailMessage 
WHERE Recipients in
    (SELECT Recipients 
     FROM EmailMessage
     GROUP BY Recipients 
     HAVING COUNT(Recipients)=1)
and sent_date > '2018-12-31 23:59:59'
and status = 'failed'

但这产生的结果太少，似乎有些不正确。我正在使用SQL Server MS。

Answer 1

当send_date> xx时，我想为不同的收件人选择ID 和状态=“某物”

这在sql中是这样翻译的：

SELECT DISTINCT Recipients  
FROM EmailMessage 
WHERE 
  sent_date > '2018-12-31 23:59:59'
  AND 
  status = 'failed'

或

SELECT Recipients  
FROM EmailMessage 
WHERE 
  sent_date > '2018-12-31 23:59:59'
  AND 
  status = 'failed'
GROUP BY Recipients

Answer 2

这将返回失败和日期条件为真的行：

SELECT em.*
FROM EmailMessage 
WHERE sent_date >= '2019-01-01' AND status = 'failed';

我不确定“不同的收件人”是什么意思。但是您可以使用窗口函数（或其他方法）为每个收件人获得一行：

SELECT em.*
FROM (SELECT em.*,
             ROW_NUMBER() OVER (PARTITION BY recipient ORDER BY sent_date) as seqnum
      FROM EmailMessage 
      WHERE sent_date >= '2019-01-01' AND status = 'failed'
     ) em
WHERE seqnum = 1;

使用where子句为不同的值选择id

2 个答案: