mysql Ò»µÀСÌâ
±íÃûΪtableµÄ±íÄÚÈÝÈçÏÂ
Year month value
2009 1 1.1
2009 2 1.2
2009 3 1.3
2009 4 1.4
2010 1 2.1
2010 2 2.2
2010 3 2.3
2010 4 2.4
ÒªÇó²éѯ½á¹ûΪ
year m1 m2 m3 m4
2009 1.1 1.2 1.3 1.4
2010 2.1 2.2 2.3 2.4
mysql> select year,sum(case when month=1 then value end) as 'm1',sum(case when m
onth=2 then value end) as 'm2',sum(case when month=3 then value end)as 'm3' from
table2 group by year;
Ïà¹ØÎĵµ£º
---- ÔÚÊý¾Ý¿âµÄÓ¦Óÿª·¢ÖУ¬³£³£»áÓöµ½ÐÔÄܺʹú¼ÛµÄÖ®¼äì¶Ü¡£ÒÔ×÷ÕßÔÚ¿ª·¢¹ÉÊÐÐÐ
Çé²éѯºÍ½»Ò×ϵͳÖÐÓöµ½µÄÎÊÌâΪÀý£¬ÒªÔÚʵʱ¼Ç¼1000¶àÖ»¹ÉƱÿ·ÖÖÓ¸üÐÂÒ»´ÎµÄÐÐ
ÇéÊý¾ÝµÄͬʱ£¬ÏìÓ¦´óÁ¿²¢·¢Óû§µÄÊý¾Ý²éѯÇëÇ󡣿¼Âǵ½ÐԼ۱ȺÍÒ×ά»¤ÐÔ£¬ÏµÍ³ÓÖ
ÒªÇóÔÚ»ùÓÚPC·þÎñÆ÷£¬Windows NTƽ̨µÄÈíÓ²¼þ»·¾³ÏÂʵÏÖ¡£¿ª ......
×î½üÔÚ×öPHPÓëÊý¾Ý¿â½»»¥µÄproject£¬¼±ÓÚÇó³É£¬Ä£·ÂÁËÏÂÀý×ӾͿªÊ¼¶¯ÊÖ£¬½á¹ûÎó°Ñmysql_fetch_arrayд³ÉÁËmysql_fetch_row,囧ÊÂÀ´ÁË£¬·¢ÏÖ·µ»ØµÄÊý×é¾ÓÈ»ÊÇindex=>valueµÄÐÎʽ£¬¶øÃ÷Ã÷¼ÇµÃÊÇfield name=>valueµÄ¹þ£¬²éÊÖ²á²ÅÃ÷°×¡£
1. mysql_fetch_arrayµÄº¯ÊýÔÐÍÊÇ
array mysql_fetch_array ( resour ......
×÷ÕߣºÒ¶½ðÈÙ£¨Email: imysql#gmail.com£©£¬À´Ô´£ºhttp://iMySQL.cn£¬×ªÔØÇë×¢Ã÷×÷Õߺͳö´¦£¬²¢ÇÒ²»ÄÜÓÃÓÚÉÌÒµÓÃ;£¬Î¥Õ߱ؾ¿¡£
MySQLÌṩÁËÊý¾Ý¿âµÄͬ²½¹¦ÄÜ£¬Õâ¶ÔÎÒÃÇʵÏÖÊý¾Ý¿âµÄÈßÔÖ¡¢±¸·Ý¡¢»Ö¸´¡¢¸ºÔؾùºâµÈ¶¼ÊÇÓм«´ó°ïÖúµÄ¡£±¾ÎÄÃèÊöÁ˳£¼ûµÄͬ²½ÉèÖ÷½·¨¡£
Ò»¡¢×¼±¸·þÎñÆ÷
ÓÉÓÚMySQL²»Í¬°æ±¾Ö®¼äµÄ(¶þ½øÖÆÈÕÖ¾)b ......
ÕâÊÇÒÔ¶ÁΪÖ÷µÄÏßÉÏ¿â
root@read 02:28:07>show status like ‘Handler_read%’;
+———————–+——-+
| Variable_name | Value |
+————&m ......
Õë¶Ôselect * from table where col1 > number order by col2 desc¡£
Æäʵ°´ÕÕ³£¹æµÄ·½·¨¿ÉÒÔÕâÑùÉè¼Æ£ºkey(col1, col2)
µ«ÊÇÕâÖÖ°ì·¨ÔÚmysqlÀï²»ËãÊÇÀíÏëµÄ£¬whereÌõ¼þÀïÏÞ¶¨Ë÷Òýǰ²¿·ÖÊÇÒ»¸ö·¶Î§µÄÇé¿öϺóÃæµÄorder by»¹ÊÇ»áÓÐfilesort¡£Èç¹ûwhereÌõ¼þÀïÏÞ¶¨Ë÷Òýǰ²¿·ÖÊÇÒ»¸ö³£Á¿£¬ÄÇôorder by¾Í»áÓÐЧÀûÓÃË÷Òý¡£À ......