SQLº¯Êý
SQLº¯Êý
ÔÚSQLÖУ¬º¯Êý¶ÔÊý¾Ý»òÊý¾Ý×éÖ´ÐвÙ×÷£¬È»ºó·µ»ØÐèÒªµÄÖµ¡£º¯Êý±í´ïʽ¿ÉÒÔ³öÏÖÔÚSELECTÁбíÖУ¬»òÕß
ÔÚÈκÎÔÊÐí³öÏÖµÄλÖÃÉÏ¡£SQL°üº¬ÁËÆßÖÖº¯Êý:
(1)¾ÛºÏº¯Êý:·µ»Ø»ã×ÜÖµ¡£
(2)תÐͺ¯Êý:½«Ò»ÖÖÊý¾ÝÀàÐÍת»»ÎªÁíÍâÒ»ÖÖ¡£
(3)ÈÕÆÚº¯Êý:´¦ÀíÈÕÆÚºÍʱ¼ä¡£
(4)Êýѧº¯Êý:Ö´ÐÐËãÊõÔËËã¡£
(5)×Ö·û´®º¯Êý:¶Ô×Ö·û´®¡¢¶þ½øÖÆÊý¾Ý»ò±í´ïʽִÐвÙ×÷¡£
(6)ϵͳº¯Êý:´ÓÊý¾Ý¿â·µ»ØÔÚSQLSERVERÖеÄÖµ¡¢¶ÔÏó»òÉèÖõÄÌØÊâÐÅÏ¢¡£
(7)Îı¾ºÍͼÏñº¯Êý:¶ÔÎı¾ºÍͼÏñÊý¾ÝÖ´ÐвÙ×÷¡£
1¡¢¾ÛºÏº¯Êý:Ëü¶ÔÆäÓ¦ÓõÄÿ¸öÐм¯·µ»ØÒ»¸öÖµ¡£
º¯Êý ·µ»ØÖµ
AVG£¨±í´ïʽ£© ·µ»Ø±í´ïʽÖÐËùÓÐµÄÆ½¾ùÖµ¡£½öÓÃÓÚÊý×ÖÁв¢×Ô¶¯ºöÂÔNULLÖµ¡£
COUNT£¨±í´ïʽ£© ·µ»Ø±í´ïʽÖзÇNULLÖµµÄÊýÁ¿¡£¿ÉÓÃÓÚÊý×ÖºÍ×Ö·ûÁС£
COUNT£¨*£© ·µ»Ø±íÖеÄÐÐÊý£¨°üÀ¨ÓÐNULLÖµµÄÁУ©¡£
MAX£¨±í´ïʽ£© ·µ»Ø±í´ïʽÖеÄ×î´óÖµ£¬ºöÂÔNULLÖµ¡£¿ÉÓÃÓÚÊý×Ö¡¢×Ö·ûºÍÈÕÆÚʱ¼äÁС£
MIN£¨±í´ïʽ£© ·µ»Ø±í´ïʽÖеÄ×îСֵ£¬ºöÂÔNULLÖµ¡£¿ÉÓÃÓÚÊý×Ö¡¢×Ö·ûºÍÈÕÆÚʱ¼ä
ÁС£
SUM£¨±í´ïʽ£© ·µ»Ø±í´ïʽÖÐËùÓеÄ×ܺͣ¬ºöÂÔNULLÖµ¡£½öÓÃÓÚÊý×ÖÁС£
2¡¢×ª»»º¯Êý:ÓÐCONVERTºÍCASTÁ½ÖÖ¡£
CONVERTʵÀý: Select convert(varchar(10) ,stuno) as stuno,stuname from student
CASTʵÀý: Select cast(stuno as varchar(10)) as stuno,stuname from student
×¢Òâ:
1)Èç¹ûûÓÐÖ¸¶¨±í´ïʽת»»ºóµÄËùµÃµ½µÄÊý¾ÝÀàÐ͵ij¤¶È£¬ÔòSQLSERVER×Ô¶¯ÌṩµÄ³¤¶ÈΪ30¡£
2)ת»»ÎªÎ»£¨bit£©ÀàÐÍʱ£¬»á½«ÈκηÇÁãֵת»»Îª1¡£
3)ת»»Îªmoney»òsmallmoneyÀàÐÍʱ£¬¼Ù¶¨»õ±Òµ¥Î»ÎªÕûÊý¡£
4)½öµ±char»òvarcharÊý¾ÝÀàÐͱíʾÊý×Öʱ£¬¿ÉÒÔת»»ÎªÕûÊýÊý¾ÝÀàÐÍ¡£
5)½«char»òvarcharÊý¾ÝÀàÐÍת»»ÎªmoneyÀàÐÍʱ£¬¿É°üº¬Ð¡ÊýµãºÍÃÀÔª·ûºÅ£¨$£©¡£
6)½«char»òvarcharÊý¾ÝÀàÐÍת»»Îª¸¡µã»òʵÊýÀàÐÍʱ£¬¿É°üº¬Ö¸Êý·ûºÅ¡£
7)Èç¹û¶ÔеÄÊý¾ÝÀàÐ͵ĶøÑÔÖµ¹ý³¤£¬ÔòÖµ½«±»½Ø¶Ï¡£
8)¿ÉÒÔÏÔʾµÄ·½·¨½«TextÁÐת»»Îªchar»òvarcharÁУ¬ÒÔ¼°½«imageÁÐת»»Îªbinary»òvarbinaryÁС£µ«ÊÇ£¬²»Äܳ¬¹ý255¸ö×Ö·û¡£
3¡¢ÈÕÆÚº¯Êý
ÓÉÓÚ²»ÄÜÖ±½ÓÖ´ÐÐËãÊõº¯Êý£¬ËùÒÔÈÕÆÚº¯Êý¾ÍÊ®·ÖÓÐÓá£
Ëü¿ÉÒÔ°ïÖúÄúÎöÈ¡³öÈÕÆÚÖµÖеÄÌì¡¢ÔºÍÄ꣬ÕâÑù¾Í¿ÉÒÔ·Ö±ð´¦ÀíËüÃÇ¡£
ÔÚSQLÖУ¬Èͮ򵀱íʾ·½·¨¼°ÓÐЧ·¶Î§£¬ÈçÏÂ:
ÈÕÆÚ²¿·Ö Ëõд Öµ ÈÕÆÚ²¿·Ö Ëõд Öµ
Ïà¹ØÎĵµ£º
±¾ÎĽéÉÜÁËSQL Server 2008ÀïһЩеÄÌØµãÒÔ¼°·¢ÏÖµÄһЩ¾«ÃîÖ®´¦……
¡¡¡¡°²×°
¡¡¡¡SQL
Server
2008µÄÉèÖúͰ²×°Ò²ÓÐËù¸Ä½ø¡£ÅäÖÃÊý¾ÝºÍÒýÇæÎ»ÒѾ·Ö¿ªÁË£¬ËùÒÔËüʹ´´½¨»ù±¾µÄδÅäÖÃϵͳµÄ´ÅÅÌͼÏñ±äµÃ¿ÉÄÜÁË£¬Ëüʹ·Ö²¼µ½¶à¸ö·þÎñÆ÷±äµÃ¸üÈÝÒ×ÁË¡£
´Ó΢ÈíµÄÕ¾µãÒ²¿ÉÒÔÕÒµ½°²×°¿ÉÓõÄ×îиüС£ÁíÒ»¸öÌØµ ......
1.sp_helpsort
SELECT SERVERPROPERTY ('Collation')
²é¿´ÄãµÄÅÅÐò¹æÔò.
²»¹ýÄãµÄÕâ¸öÓ¦¸ÃºÍ×Ö·û¼¯ÓйØ.
2.¸ü¸Ä·þÎñÆ÷ÅÅÐò¹æÔò
¸ü¸Ä SQL Server 2005 ʵÀýµÄĬÈÏÅÅÐò¹æÔòµÄ²Ù×÷¿ÉÄÜ»á±È½Ï¸´ÔÓ£¬°üÀ¨ÒÔϲ½Ö裺
È·±£¾ßÓÐÖØÐ´´½¨Óû§Êý¾Ý¿â¼°ÕâЩÊý¾Ý¿âÖеÄËùÓжÔÏóËùÐèµÄÈ«²¿ÐÅÏ¢»ò½Å±¾¡£
ʹÓù¤¾ß£¨ÀýÈç´óÈÝÁ ......
ͨ¹ýv$sqlarea,v$sql²éѯ×îÕ¼ÓÃ×ÊÔ´µÄ²éѯ ÊÕ²Ø
ÒýÓÃ:http://blog.chinaunix.net/u/3866/showart_396335.html
-----------------------
v$sqlarea,v$sql
-----------------------
´ÓV$SQLAREAÖвéѯ×îÕ¼ÓÃ×ÊÔ´µÄ²éѯ
select b.username username,a.disk_reads reads,
a.executions exec,a ......
ʹÓÃSQL ServerÉí·ÝÑéÖ¤µÇ¼ʱ±¨´í£º
ÎÞ·¨Á¬½Óµ½.\SQLEXPRESS.
Additional information:
Óû§'sa'µÇ¼ʧ°Ü¡£¸ÃÓû§Óë¿ÉÐÅSQL Server Á¬½ÓÎÞ¹ØÁª¡£(microsoft SQL Server,Error:18452£©)
------------------
ÏÂÃæÊÇÓ³Éäʱ±¨µÄ´í£º
´´½¨¶ÔÓÚÓû§“sa”ʧ°Ü¡££¨microsoft.sqlServer.express.smo£©
Additional ......
ÓÅ»¯Æ÷ÔÚÐγÉÖ´Ðмƻ®Ê±ÐèÒª×öµÄÒ»¸öÖØÒªÑ¡ÔñÊÇÈçºÎ´ÓÊý¾Ý¿â²éѯ³öÐèÒªµÄÊý¾Ý¡£¶ÔÓÚSQLÓï¾ä´æÈ¡µÄÈκαíÖеÄÈκÎÐУ¬¿ÉÄÜ´æÔÚÐí¶à´æÈ¡Â·¾¶(´æÈ¡·½·¨)£¬Í¨¹ýËüÃÇ¿ÉÒÔ¶¨Î»ºÍ²éѯ³öÐèÒªµÄÊý¾Ý¡£ÓÅ»¯Æ÷Ñ¡ÔñÆäÖÐ×ÔÈÏΪÊÇ×îÓÅ»¯µÄ·¾¶¡£
¡¡¡¡ÔÚÎïÀí²ã£¬oracle¶ÁÈ¡Êý¾Ý£¬Ò»´Î¶ÁÈ¡µÄ×îСµ¥Î»ÎªÊý¾Ý¿â¿é(Óɶà¸öÁ¬ÐøµÄ²Ù×÷ϵͳ¿é×é³É ......