Question

我有一张这样的表：

| id      | certificate|expires   |
|       1 |        123 |12-DEC-15 | 
|       1 |        123 |12-DEC-09 |
|       1 |        123 |13-DEC-09 |
|       2 |        456 |14-DEC-16 |
|       2 |        456 |14-DEC-09 |
|       2 |        789 |14-DEC-09 |
|       2 |        789 |14-DEC-09 |

我正在尝试将每个已过期但尚未过期的用户的证书数量相加：

 |id | expired | unexpired |
 |1  |2        |1          |
 |2  |3        |1          |

我已经设法计算所有已过期的证书，但它只会输出未过期的行数。我如何获得过期证书的数量？

   SELECT 
      id, 
      COUNT(certificate) as numcerts, 
      expires
   FROM 
     certificates
   WHERE 
     expires > current_date()
  GROUP BY id
  having numcerts > 0
  ORDER BY COUNT(*) DESC

Answer 1

如果日期存储在date数据类型中，则以下查询将为您提供结果

select 
id, 
sum( case when expires < curdate() then 1 else 0 end ) as expires,
sum( case when expires > curdate() then 1 else 0 end ) as unsepired 
from certificates group by id

如果日期以给定示例中的方式存储为varchar，那么您需要使用str_to_date函数

select 
id, 
sum( case when str_to_date(expire,'%d-%b-%y') < curdate() then 1 else 0 end ) as expires,
sum( case when str_to_date(expire,'%d-%b-%y') > curdate() then 1 else 0 end ) as unsepired 
from certificates group by id

计算过期的数量＆amp;每个唯一ID的未过期行

1 个答案: