MySql ±íµÄÖ÷¼üË÷ÒýÎÊÌâ
²é¿´Ä³¸ö±íµÄ½¨±íÓï¾ä £ºshow create table data_statdata;
drop index ts on data_statdata;
Ë÷ÒýÊǼÓËÙ²éѯµÄÖ÷ÒªÊֶΣ¬Ìرð¶ÔÓÚÉæ¼°¶à¸ö±íµÄ²éѯ¸üÊÇÈç´Ë¡£±¾½ÚÖУ¬½«½éÉÜË÷ÒýµÄ×÷Óá¢Ìص㣬ÒÔ¼°´´½¨ºÍɾ³ýË÷ÒýµÄÓï·¨¡£
13.4.1 ʹÓÃË÷ÒýÓÅ»¯²éѯ
Ë÷ÒýÊÇ¿ìËÙ¶¨Î»Êý¾ÝµÄ¼¼Êõ£¬Ê×ÏÈͨ¹ýÒ»¸öʾÀýÀ´Á˽âÆ京Òå¼°×÷Óã¬ÏêϸµÄ½éÉÜÇë²Î¿¼µÚ14Õ¡£
1£®Ë÷ÒýʾÀý
¼ÙÉè¶ÔÓÚ10.3½ÚËù½¨µÄ±í£¬¸÷¸ö±íÉ϶¼Ã»ÓÐË÷Òý£¬Êý¾ÝµÄÅÅÁÐҲûÓйæÂÉ£¬Èç±í13.3Ëùʾ¡£
±í13.3 ûÓÐË÷ÒýµÄstudents±í
sid
sname
sgender
sage
52
zhang
M
21
22
wang
M
22
33
li
F
19
41
zhao
M
20
...
...
...
µ±²éÕÒij¸öѧÉúÐÅϢʱ£¬±ØÐë˳Ðò²é¿´±ístudentsÖеÄÿһÐУ¬¼ì²éÊÇ·ñÓëËùÐèֵƥÅ䣬ÕâÐèҪɨÃèÈ«±í£¬Ð§Âʺܵ͡£
±í13.4¸ø³öÁËÔÚnameÁÐÉÏÔö¼ÓÁËË÷ÒýµÄstudents±í¡£
±í13.4 ÔÚnameÁÐÉÏÔö¼ÓÁËË÷ÒýµÄstudents±í
Ë÷ÒýÊÇÔÚnameÉÏÅÅÐòµÄ¡£ÏÖÔÚ£¬µ±²éÕÒij¸öѧÉúÐÅϢʱ£¬¾Í²»ÐèÒªÖðÐÐËÑË÷È«±í£¬¿ÉÒÔÀûÓÃË÷Òý½øÐÐÓÐÐò²éÕÒ£¨Èç¶þ·Ö²éÕÒ·¨£©£¬²¢¿ìËÙ¶¨Î»µ½Æ¥ÅäµÄÖµ£¬ÒÔ½ÚÊ¡´óÁ¿ËÑË÷ʱ¼ä¡£
2£®Ë÷Òý×÷ÓÃ
ÔÚË÷ÒýÁÐÉÏ£¬³ýÁËÉÏÃæÌáµ½µÄÓÐÐò²éÕÒÖ®Í⣬Êý¾Ý¿âÀûÓø÷ÖÖ¸÷ÑùµÄ¿ìËÙ¶¨Î»¼¼Êõ£¬Äܹ»´ó´óÌá¸ß²éѯЧÂÊ¡£ÌرðÊǵ±Êý¾ÝÁ¿·Ç³£´ó£¬²éѯÉæ¼°¶à¸ö±íʱ£¬Ê¹ÓÃË÷ÒýÍùÍùÄÜʹ²éѯËٶȼӿì³ÉǧÉÏÍò±¶¡£
ÀýÈ磬ÓÐ3¸öδË÷ÒýµÄ±ít1¡¢t2¡¢t3£¬·Ö±ðÖ»°üº¬ÁÐc1¡¢c2¡¢c3£¬Ã¿¸ö±í·Ö±ðº¬ÓÐ1000ÐÐÊý¾Ý×é³É£¬Ö¸Îª1¡«1000µÄÊýÖµ£¬²éÕÒ¶ÔÓ¦ÖµÏàµÈÐеIJéѯÈçÏÂËùʾ¡£
SELECT c1,c2,c3 from t1,t2,t3 WHERE c1=c2 AND c1=c3
´Ë²éѯ½á¹ûÓ¦¸ÃΪ1000ÐУ¬Ã¿Ðаüº¬3¸öÏàµÈµÄÖµ¡£ÔÚÎÞË÷ÒýµÄÇé¿öÏ´¦Àí´Ë²éѯ£¬±ØÐëÑ°ÕÒ3¸ö±íËùÓеÄ×éºÏ£¬ÒÔ±ãµÃ³öÓëWHERE×Ó¾äÏàÅäµ
Ïà¹ØÎĵµ£º
ʾÀý£º
create procedure proc_name (in parameter integer)
begin
declare variable varchar(20);
if parameter=1 then
set variable='MySQL';
else
set variable='PHP';
end if;
insert into tb (name) values (variable);
end;
MySQLÀ©Õ¹Ò²ÊÇÖ§³Ö´æ´¢¹ý³ÌµÄ£¬²»¹ýÖ»Ö§³ÖÎÞ·µ»Ø½á¹ûµÄ´æ´¢¹ý³Ì
¿ÉÒÔÊ¹Ó ......
1.¶Ô²éѯ½øÐÐÓÅ»¯£¬Ó¦¾¡Á¿±ÜÃâÈ«±íɨÃ裬Ê×ÏÈÓ¦¿¼ÂÇÔÚ where ¼° order by Éæ¼°µÄÁÐÉϽ¨Á¢Ë÷Òý¡£
2.Ó¦¾¡Á¿±ÜÃâÔÚ where ×Ó¾äÖжÔ×ֶνøÐÐ null ÖµÅжϣ¬·ñÔò½«µ¼ÖÂÒýÇæ
·ÅÆúʹÓÃË÷Òý¶ø½øÐÐÈ«±íɨÃ裬È磺
select id from t where num is null
¿ÉÒÔÔÚnumÉÏÉèÖÃ
ĬÈÏÖµ0£¬È·±£±íÖÐnumÁÐûÓÐnullÖµ£¬È»ºóÕâ
Ñù²éѯ£º
sel ......
MYSQLºÍORACLEµÄһЩ²Ù×÷Çø±ð
ÓкܶàÓ¦ÓÃÏîÄ¿, ¸ÕÆð²½µÄʱºòÓÃMYSQLÊý¾Ý¿â»ù±¾ÉÏÄÜʵÏÖ¸÷ÖÖ¹¦ÄÜÐèÇó£¬Ëæ×ÅÓ¦ÓÃÓû§µÄÔö¶à£¬Êý¾ÝÁ¿µÄÔö¼Ó£¬MYSQL½¥½¥µØ³öÏÖ²»¿°ÖظºµÄÇé¿ö£ºÁ¬½ÓºÜÂýÉõÖÁå´»ú£¬ÓÚÊǾÍÓаÑÊý¾Ý´ÓMYSQLǨµ½ORACLEµÄÐèÇó£¬Ó¦ÓóÌÐòÒ²ÒªÏàÓ¦×öһЩÐ޸ġ£±¾ÈË×ܽá³öÒÔϼ¸µã×¢ÒâÊÂÏϣÍû¶Ô´ó¼ÒÓÐËù°ïÖú¡£
1.×Ô ......
×öһЩÊý¾Ý¿â²éѯ£¬²»½öÏ£ÍûµÃµ½Òª²éѯµÄ½á¹û£¬»¹Ï£Íû·½±ãµØͳ¼Æһϲéѯ½á¹ûÖÐÓжàÉÙÌõ¼Ç¼¡£ÎÒͨ³£µÄ×ö·¨ÊÇ£º
$q = "select * from $fromTable where $where limit $start,$pageSize";
$r = mysql_query($q);
$q = "select count(*) from $fromTable where $where";
$cnt = mysql_query($q);
µ± ......