作者热门文章
- html - 出于某种原因,IE8 对我的 Sass 文件中继承的 html5 CSS 不友好?
- JMeter 在响应断言中使用 span 标签的问题
- html - 在 :hover and :active? 上具有不同效果的 CSS 动画
- html - 相对于居中的 html 内容固定的 CSS 重复背景?
考虑下表:
un_id avl_id avl_date avl_status
1738 6377398 2011-03-10 unavailable
1738 6377399 2011-03-11 unavailable
1738 6377400 2011-03-12 unavailable
1738 6719067 2011-03-12 unavailable
1738 6719351 2011-03-12 available
1738 6377401 2011-03-13 unavailable
1738 6377402 2011-03-14 unavailable
1738 6377403 2011-03-15 unavailable
1738 6377404 2011-03-16 available
1738 6719068 2011-03-16 unavailable
1738 6719352 2011-03-16 available
这是从以下查询中获得的:
SELECT
tbl_unit.un_id,
tbl_availability.avl_id,
tbl_availability.avl_date,
tbl_availability.avl_status
FROM
tbl_unit
INNER JOIN
tbl_availability ON
tbl_unit.un_id = tbl_availability.un_id
WHERE
tbl_availability.avl_active='True' AND
tbl_unit.un_active='True' AND
tbl_availability.avl_date >= '2011-03-10' AND
tbl_availability.avl_date
<p>What I want is to GROUP BY un_id so that only the avl_status having the highest avl_id is displayed. i.e:</p>
un_id avl_id avl_date avl_status
1738 6377398 2011-03-10 unavailable
1738 6377399 2011-03-11 unavailable
1738 6719351 2011-03-12 available
1738 6377401 2011-03-13 booked
1738 6377402 2011-03-14 booked
1738 6377403 2011-03-15 booked
1738 6719352 2011-03-16 available
我尝试添加 GROUP BY 和 HAVING 子句以及各种子查询,但每次都失败了....
感谢所有帮助! :)- 亚当。
最佳答案
SELECT
tbl_unit.un_id,
tbl_availability.avl_id,
tbl_availability.avl_date,
tbl_availability.avl_status
FROM
tbl_unit
INNER JOIN
(select un_id, max(avl_id) as max_avl_id from tbl_availability group by un_id) T
on tbl_unit.un_id = T.un_id
INNER JOIN tbl_availability ON
T.max_avl_id = tbl_availability.avl_id
WHERE
tbl_availability.avl_active='True' AND
tbl_unit.un_active='True' AND
tbl_availability.avl_date >= '2011-03-10' AND
tbl_availability.avl_date
关于MySQL Group by a field based on another field maximum value of another field IN THE GROUP(不在表中),我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/5274543/
我是一名优秀的程序员,十分优秀!