我有一个数据表,表结构如下
datetime | t(温度)| p(湿度)
2008-06-06 01:00:00 | 19 | 50
2008-06-06 02:00:00 | 21 | 80
2008-06-06 03:00:00 | 20 | 40我想用一条语句查出温度和湿度的最大值最小值及温度、湿度最大值、最小值出现的时间。请高手指教...
datetime | t(温度)| p(湿度)
2008-06-06 01:00:00 | 19 | 50
2008-06-06 02:00:00 | 21 | 80
2008-06-06 03:00:00 | 20 | 40我想用一条语句查出温度和湿度的最大值最小值及温度、湿度最大值、最小值出现的时间。请高手指教...
LEFT JOIN
(SELECT MAX(温度) AS WMA,MIN(温度) AS WMI,MAX(湿度) AS SMA,MIN(湿度) AS SMI FROM TT) B
ON A.温度=WMA
LEFT JOIN TT C ON B.WMI=C.温度
LEFT JOIN TT D ON B.SMA=D.湿度
LEFT JOIN TT E ON B.SMI=E.湿度
select time,t from wendu where t=(select max(t) from wendu);
.
[align=center]==== 思想重于技巧 ====
[/align]
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贴子分数<20:对自已的问题不予重视。
贴子大量未结:对别人的回答不予尊重。
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select a.t as t_max, a.datetime as t_max_time,
b.t as t_min, b.datetime as t_min_time,
c.s as s_max, c.datetime as s_max_time,
d.s as s_min, d.datetime as s_min_time
from
(select t, datetime from table1 where t=(select max(t) from table1)) a,
(select t, datetime from table1 where t=(select min(t) from table1)) b,
(select s, datetime from table1 where s=(select min(s) from table1)) c,
(select s, datetime from table1 where s=(select min(s) from table1)) d
建表时不要以关键字作为字段名
比如 datetime以上结果可以进行行列转换一下 那样更直观
不过我不太会