SQL code:
<p align="center"><img title="2222222222222" height="200" alt="2222222222222" src="../UpLoadFolder/201056221026166491.gif" width="200" border="0" /></p>
ÓÐÕâÖÖÀàÐ͵Ä×Ö·û´®
ÎÒÏë°ÑÀïÃæµÄ 2010562210261 ......
Çë½Ì...
C1 C2 C3
1 yy 1
1 yy 4
1 yy 2
2 de 3
2 de 2
2 de 1
3 s 2
3 s 4
3 s 2
4 yy 1
4 yy 2
4 yy 5
Êä³öC1,AVG(C3),C2, GROUP BY C1µÄSQL¸ÃÔõÃ´Ð´ÄØ?
select C1,AVG(C3),C2 group by C1,C2
..ÅóÓÑÒѽâ´ð...- -
½áT~
ModBusÐÒé½éÉÜ
²»ºÃÒâ˼¸ã´íÁË£º£©
http: ......
ÎÒÏë×öÒ»¸öÂÛ̳
Êý¾Ý¿âÖÐÓÐÒ»¸ö¼Ç¼µã»÷µÄ±í
ÔÚÕâ¸ö±íÀïÓÐÕâôÁ½¸ö×Ö¶Î
topicId -- Õâ¸ö×Ö¶ÎÊÇÖ¸µã»÷ÁËÄĸöÌû×ÓµÄID
clickTime -- µã»÷ʱ¼ä
±íµÄÄÚÈÝ´óÖÂÈçÏÂ:
id clickTime
1 2010.1.1
1 2010.2.1
2 2010.1.3
1 2010.1.3
3 2010.1.5
1 2010.1.1
1 2010.1.3
3 2010.1.1
2 2010.1.3
3 2010.1.2
ÎÒ¾ÍÊ ......
ÁÐA£¬ÁÐB
a1,1
a1,2
a1,3
a2,1
a2,2
a3,1
a4,2
..
..
È¡
ÁÐA=a1ÀïÁÐB×î´óµÄ
ÁÐA=a2ÀïÁÐB×î´óµÄ
¡£¡£¡£¡£
select a ,max(b) as maxb from table group by a
select a, max(b)
from tb
group by a
ÒýÓÃ
select a ,max(b) as maxb from table group by a
Áкܶࡣ
ÎÒÏëд select * ÄØ£¿
SQL code: ......
²éѯ×îÐÂ10ÌõÊý¾Ý£¬Ê±¼ä°´ÉýÐòÅÅÁУ¬Èô²»¹»10Ìõ£¬ÏÔʾ´æÔÚµÄÊý¾Ý
SQL code:
select top 10 * from [Table] order by ʱ¼ä desc
ÎÒÏ밴ʱ¼äÉýÐòÅÅÁÐ
select top 10 * from [Table] order by ʱ¼ä
3Â¥Àí½â´íÎó
ÎÒµÄÒâ˼²éѯ³ö×îºó10ÌõÊý¾Ýºó£¬È»ºóÔÙ°´Ê±¼äÈÃËüÏÔʾ
Χ¹Û£¡
û¿´¶®Ê²Ã´Òâ˼
SQL code:
......
±íÊý¾Ý
id pid name
1 0 a
2 0 b
3 1 c
4 1 d
5 0 e
6 3 f
7 3 g
ÒªµÃµ½ top 5
id pid name top
1 0 a top1
|-3 1 c
|-6 3 f
|-7 3 g
|-4 1 d
2 0 ......