SQLÁª±í¸üУ¬Áª±í²éѯ
ûÓÐÒýÓùØÏµµÄ±í
£±.¡¡Áª±í¸üÐÂ
update a set a.education = '±¾¿Æ' from NT_UserInfo a ,NT_User b where a.UserID=b.UserID and b.email = 'carlfan2008@163.com'
£².¡¡Áª±í²éѯ
select a.*,b.* from nt_user as a, nt_userinfo as b where a.userid = b.userid and Email = 'carlfan2008@163.com'
Ïà¹ØÎĵµ£º
SQLÖÐonÌõ¼þÓëwhereÌõ¼þµÄÇø±ð
Êý¾Ý¿âÔÚͨ¹ýÁ¬½ÓÁ½ÕÅ»ò¶àÕűíÀ´·µ»Ø¼Ç¼ʱ£¬¶¼»áÉú³ÉÒ»ÕÅÖмäµÄÁÙʱ±í£¬È»ºóÔÙ½«ÕâÕÅÁÙʱ±í·µ»Ø¸øÓû§¡£
ÔÚʹÓÃleft jionʱ£¬onºÍwhereÌõ¼þµÄÇø±ðÈçÏ£º
1¡¢ onÌõ¼þÊÇÔÚÉú³ÉÁÙʱ±íʱʹÓõÄÌõ¼ ......
½»²æ±íÓï¾äµÄʵÏÖ:
¡¡¡¡ÓÃÓÚ:½»²æ±íµÄÁÐÊýÊÇÈ·¶¨µÄ
¡¡¡¡select name,sum(case subject when 'Êýѧ' then source else 0 end) as 'Êýѧ',
¡¡¡¡sum(case subject when 'Ó¢Óï' then source else 0 end) as 'Ó¢Óï',
¡¡¡¡sum(case subject when 'ÓïÎÄ' then source else 0 end) as 'ÓïÎÄ'
¡¡¡¡from test
¡¡¡¡group by name ......
http://cheneyph.javaeye.com/blog/477829
ÔÚJavaÖУ¬»ñµÃResultSetµÄ×ÜÐÐÊýµÄ·½·¨ÓÐÒÔϼ¸ÖÖ¡£
µÚÒ»ÖÖ£ºÀûÓÃResultSetµÄgetRow·½·¨À´»ñµÃResultSetµÄ×ÜÐÐÊý
Statement stmt = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_UPDATABL ......
Ò»¡¢×Ö·ûת»»º¯Êý
1¡¢ASCII()
·µ»Ø×Ö·û±í´ïʽ×î×ó¶Ë×Ö·ûµÄASCII ÂëÖµ¡£ÔÚASCII£¨£©º¯ÊýÖУ¬´¿Êý×ÖµÄ×Ö·û´®¿É²»ÓÑ’À¨ÆðÀ´£¬µ«º¬ÆäËü×Ö·ûµÄ×Ö·û´®±ØÐëÓÑ’À¨ÆðÀ´Ê¹Ó㬷ñÔò»á³ö´í¡£
2¡¢CHAR()
½«ASCII Âëת»»Îª×Ö·û¡£Èç¹ûûÓÐÊäÈë0 ~ 255 Ö®¼äµÄASCII ÂëÖµ£¬CHAR£¨£© ·µ»ØNULL ¡£
3¡¢LOWER()ºÍ ......
ÔÚSQLÖÐSelectÓï¾äµÄÖ´ÐÐ˳ÐòÈçÏ£º
(1)from×Ӿ䣬×é×°À´×Ô²»Í¬Êý¾ÝÔ´µÄÊý¾Ý
(2)WHERE×Ӿ䣬¸øÓèÖ¸¶¨Ìõ¼þ¶Ô¼Ç¼½øÐÐɸѡ
(3)GROUP BY×Ӿ䣬½«Êý¾Ý»®·ÖΪ¶à¸ö×é
(4)ʹÓþۼ¯º¯Êý½øÐмÆËã
(5)ʹÓÃHAVING×Ó¾äɸѡ·Ö×é
(6)¼ÆËãËùÓбí´ïʽ
(7)ʹÓÃORDER BY¶Ô½á¹û½øÐÐÅÅÐò ......