锘??xml version="1.0" encoding="utf-8" standalone="yes"?>亚洲欧洲动漫,蜜臀久久99精品久久久久久宅男 ,免费在线性爱视频http://www.aygfsteel.com/yaya/category/27082.htmlzh-cnTue, 15 Apr 2008 19:28:13 GMTTue, 15 Apr 2008 19:28:13 GMT60SQL涓璫har銆乿archar銆乼ext鍜宯char銆乶varchar銆乶text鐨勫尯鍒?/title><link>http://www.aygfsteel.com/yaya/archive/2008/04/14/192934.html</link><dc:creator>涓斧</dc:creator><author>涓斧</author><pubDate>Mon, 14 Apr 2008 14:21:00 GMT</pubDate><guid>http://www.aygfsteel.com/yaya/archive/2008/04/14/192934.html</guid><wfw:comment>http://www.aygfsteel.com/yaya/comments/192934.html</wfw:comment><comments>http://www.aygfsteel.com/yaya/archive/2008/04/14/192934.html#Feedback</comments><slash:comments>0</slash:comments><wfw:commentRss>http://www.aygfsteel.com/yaya/comments/commentRss/192934.html</wfw:commentRss><trackback:ping>http://www.aygfsteel.com/yaya/services/trackbacks/192934.html</trackback:ping><description><![CDATA[SQL涓璫har銆乿archar銆乼ext鍜宯char銆乶varchar銆乶text鐨勫尯鍒?br />      1銆丆HAR銆侰HAR瀛樺偍瀹氶暱鏁版嵁寰堟柟渚匡紝CHAR瀛楁涓婄殑绱㈠紩鏁堢巼綰ч珮錛屾瘮濡傚畾涔塩har(10)錛岄偅涔堜笉璁轟綘瀛樺偍鐨勬暟鎹槸鍚﹁揪鍒頒簡10涓瓧鑺傦紝閮借鍗犲幓10涓瓧鑺傜殑絀洪棿銆?br />      2銆乂ARCHAR銆傚瓨鍌ㄥ彉闀挎暟鎹紝浣嗗瓨鍌ㄦ晥鐜囨病鏈塁HAR楂樸傚鏋滀竴涓瓧孌靛彲鑳界殑鍊兼槸涓嶅浐瀹氶暱搴︾殑錛屾垜浠彧鐭ラ亾瀹冧笉鍙兘瓚呰繃10涓瓧絎︼紝鎶婂畠瀹氫箟涓?VARCHAR(10)鏄渶鍚堢畻鐨勩俈ARCHAR綾誨瀷鐨勫疄闄呴暱搴︽槸瀹冪殑鍊肩殑瀹為檯闀垮害+1銆備負(fù)浠涔?#8220;+1”鍛紵榪欎竴涓瓧鑺傜敤浜庝繚瀛樺疄闄呬嬌鐢ㄤ簡澶氬ぇ鐨勯暱搴︺?br />     浠庣┖闂翠笂鑰冭檻錛岀敤varchar鍚堥傦紱浠庢晥鐜囦笂鑰冭檻錛岀敤char鍚堥傦紝鍏抽敭鏄牴鎹疄闄呮儏鍐墊壘鍒版潈琛＄偣銆?br />     3銆乀EXT銆倀ext瀛樺偍鍙彉闀垮害鐨勯潪Unicode鏁版嵁錛屾渶澶ч暱搴︿負(fù)2^31-1(2,147,483,647)涓瓧絎︺?br />      4銆丯CHAR銆丯VARCHAR銆丯TEXT銆傝繖涓夌浠庡悕瀛椾笂鐪嬫瘮鍓嶉潰涓夌澶氫簡涓?#8220;N”銆傚畠琛ㄧず瀛樺偍鐨勬槸Unicode鏁版嵁綾誨瀷鐨勫瓧絎︺傛垜浠煡閬撳瓧絎︿腑錛岃嫳鏂囧瓧絎﹀彧闇瑕佷竴涓瓧鑺傚瓨鍌ㄥ氨瓚沖浜嗭紝浣嗘眽瀛椾紬澶氾紝闇瑕佷袱涓瓧鑺傚瓨鍌紝鑻辨枃涓庢眽瀛楀悓鏃跺瓨鍦ㄦ椂瀹規(guī)槗閫犳垚娣蜂貢錛孶nicode瀛楃闆嗗氨鏄負(fù)浜嗚В鍐沖瓧絎﹂泦榪欑涓嶅吋瀹圭殑闂鑰屼駭鐢熺殑錛屽畠鎵鏈夌殑瀛楃閮界敤涓や釜瀛楄妭琛ㄧず錛屽嵆鑻辨枃瀛楃涔熸槸鐢ㄤ袱涓瓧鑺傝〃紺恒俷char銆乶varchar鐨勯暱搴︽槸鍦?鍒?000涔嬮棿銆傚拰char銆乿archar姣旇緝璧鋒潵錛宯char銆乶varchar鍒欐渶澶氬瓨鍌?000涓瓧絎︼紝涓嶈鏄嫳鏂囪繕鏄眽瀛楋紱鑰宑har銆乿archar鏈澶氳兘瀛樺偍8000涓嫳鏂囷紝4000涓眽瀛椼傚彲浠ョ湅鍑轟嬌鐢╪char銆乶varchar鏁版嵁綾誨瀷鏃朵笉鐢ㄦ媴蹇冭緭鍏ョ殑瀛楃鏄嫳鏂囪繕鏄眽瀛楋紝杈冧負(fù)鏂逛究錛屼絾鍦ㄥ瓨鍌ㄨ嫳鏂囨椂鏁伴噺涓婃湁浜涙崯澶便?br />      鎵浠ヤ竴鑸潵璇達(dá)紝濡傛灉鍚湁涓枃瀛楃錛岀敤nchar/nvarchar錛屽鏋滅函鑻辨枃鍜屾暟瀛楋紝鐢╟har/varchar銆?br /> <br /> <br /> <hr /> <br /> <br /> <br /> 鏁版嵁搴撳畾涔夊埌char綾誨瀷鐨勫瓧孌墊椂 char銆乶char銆乿archar銆乶varchar銆乼ext銆乶text涓摢涓縐嶅憿 <br /> 銆鏁版嵁搴撳畾涔夊埌char綾誨瀷鐨勫瓧孌墊椂錛屼笉鐭ラ亾澶у鏄惁浼?xì)鐘硅鲍涓涓嬶紝鍒板簳閫塩har銆乶char銆乿archar銆乶varchar銆乼ext銆乶text涓摢涓縐嶅憿錛熺粨鏋滃緢鍙兘鏄袱縐嶏紝涓縐嶆槸鑺備凱浜哄＋鐨勯夋嫨錛氭渶濂芥槸鐢ㄥ畾闀跨殑錛屾劅瑙夋瘮鍙橀暱鑳界渷浜涚┖闂達(dá)紝鑰屼笖澶勭悊璧鋒潵浼?xì)蹇簺锛屾棤娉曞畾闀垮彧濂介夌敤瀹氶暱錛屽茍涓斿皢闀垮害璁劇疆灝藉彲鑳藉湴灝忥紱鍙︿竴縐嶆槸鍒欐槸瑙夊緱鏃犳墍璋擄紝灝介噺鐢ㄥ彲鍙樼被鍨嬬殑錛岄暱搴﹀敖閲忔斁澶т簺銆?<br /> <br /> 銆銆閴翠簬鐜板湪紜歡鍍忚悵鍗滀竴鏍蜂究瀹滅殑澶уソ褰㈠娍錛岀籂緙犺繖鏍風(fēng)殑灝忛棶棰樺疄鍦ㄦ槸娌″澶ф剰涔夛紝涓嶈繃濡傛灉涓嶅紕娓呭畠錛屾昏寰楀涓嶈搗鍔崇瘡榪囧害鐨凜PU鍜岀‖鐩樸?<br /> <br /> 涓嬮潰寮濮嬩簡(浠ヤ笅璇存槑鍙拡瀵筍qlServer鏈夋晥)錛?<br /> <br /> 1銆佸綋浣跨敤闈瀠nicode鏃舵厧鐢ㄤ互涓嬭繖縐嶆煡璇細(xì) <br />               select f from t where f = N'xx' <br /> <br />       鍘熷洜錛氭棤娉曞埄鐢ㄥ埌绱㈠紩錛屽洜涓烘暟鎹簱浼?xì)灏唂鍏堣漿鎹㈠埌unicode鍐嶅拰N'xx'姣旇緝 <br /> <br /> 2銆乧har 鍜岀浉鍚岄暱搴︾殑varchar澶勭悊閫熷害宸笉澶氾紙鍚庨潰榪樻湁璇存槑錛?<br /> <br /> 3銆乿archar鐨勯暱搴︿笉浼?xì)濯勫搷澶勭悊閫熷害錛侊紒錛侊紙鐪嬪悗闈㈣В閲婏級 <br /> <br /> 4銆佺儲寮曚腑鍒楁婚暱搴︽渶澶氭敮鎸佹諱負(fù)900瀛楄妭錛屾墍浠ラ暱搴﹀ぇ浜?00鐨剉archar銆乧har鍜屽ぇ浜?50鐨刵varchar,nchar灝嗘棤娉曞垱寤虹儲寮?<br /> <br /> 5銆乼ext銆乶text涓婃槸鏃犳硶鍒涘緩绱㈠紩鐨?<br /> <br /> 6銆丱/R Mapping涓搴斿疄浣撶殑灞炴х被鍨嬩竴鑸槸浠tring灞呭錛岀敤char[]鐨勯潪甯稿皯錛屾墍浠ュ鏋滄寜mapping鐨勫悎鐞嗘ф潵璇達(dá)紝鍙彉闀垮害鐨勭被鍨嬫洿鍔犲惢鍚?<br /> <br /> 7銆佷竴鑸熀紜璧勬枡琛ㄤ腑鐨刵ame鍦ㄥ疄闄呮煡璇腑鍩烘湰涓婂叏閮ㄦ槸浣跨敤like '%xx%'榪欑鏂瑰紡錛岃岃繖縐嶆柟寮忔槸鏃犳硶鍒╃敤绱㈠紩鐨勶紝鎵浠ュ鏋滃浜庢縐嶅瓧孌碉紝绱㈠紩寤轟簡涔熺櫧寤?<br /> <br /> 8銆佸叾瀹冧竴浜涘儚remark鐨勫瓧孌靛垯鏄牴鏈笉闇瑕佹煡璇㈢殑錛屾墍浠ヤ笉闇瑕佺儲寮?<br /> <br /> 9銆乿archar鐨勫瓨鏀懼拰string鏄竴鏍峰師鐞嗙殑錛屽嵆length {block}榪欑鏂瑰紡錛屾墍浠archar鐨勯暱搴﹀拰瀹冨疄闄呭崰鐢ㄧ┖闂存槸鏃犲叧鐨?<br /> <br /> 10銆佸浜庡浐瀹氶暱搴︾殑瀛楁錛屾槸闇瑕侀澶栫┖闂存潵瀛樻斁NULL鏍囪瘑鐨勶紝鎵浠ュ鏋滀竴涓猚har瀛楁涓嚭鐜伴潪甯稿鐨凬ULL錛岄偅涔堝緢涓嶅垢錛屼綘鐨勫崰鐢ㄧ┖闂存瘮娌℃湁NULL鐨勫ぇ錛堜絾榪欎釜澶у茍涓嶆槸澶уお澶氾紝鍥犱負(fù)NULL鏍囪瘑鏄敤bit瀛樻斁鐨勶紝鍙槸濡傛灉浣犱竴琛屼腑鍙湁浣犱竴涓狽ULL闇瑕佹爣璇嗭紝閭ｄ箞浣犲氨鐧界櫧嫻垂1byte絀洪棿浜嗭紝緗繃緗繃錛侊級錛岃繖鏃跺欙紝浣犲彲浠ヤ嬌鐢ㄧ壒孌婃爣璇嗘潵瀛樻斁錛屽錛?NV' <br /> <br /> 11銆佸悓涓婏紝鎵浠ュ浜庤繖縐峃ULL鏌ヨ錛岀儲寮曟槸鏃犳硶鐢熸晥鐨勶紝鍋囧浣犱嬌鐢ㄤ簡NULL鏍囪瘑鏇夸唬鐨勮瘽錛岄偅涔堟伃鍠滀綘錛屼綘鍙互鍒╃敤鍒扮儲寮曚簡 <br /> <br /> 12銆乧har鍜寁archar鐨勬瘮杈冩垚鏈槸涓鏍風(fēng)殑錛岀幇鍦ㄥ叧閿氨鐪嬪畠浠殑绱㈠紩鏌ユ壘鐨勬垚鏈簡錛屽洜涓烘煡鎵劇瓥鐣ラ兘涓鏍鳳紝鍥犳搴旇姣旇緝璋佸崰鐢ㄧ┖闂村皬銆傚湪瀛樻斁鐩稿悓鏁伴噺鐨勫瓧絎︽儏鍐典笅錛屽鏋滄暟閲忓皬錛岄偅涔坈har鍗犵敤闀垮害鏄皬浜巚archar鐨勶紝浣嗗鏋滄暟閲忕◢澶э紝鍒檝archar瀹屽叏鍙兘灝忎簬char錛岃屼笖瑕佺湅瀹為檯濉厖鏁板肩殑鍏呭疄搴︼紝姣斿璇磛archar(3)鍜宑har(3)錛岄偅涔堢悊璁轟笂搴旇鏄痗har蹇簡錛屼絾濡傛灉鏄痗har(10)鍜寁archar(10)錛屽厖瀹炲害鍙湁30%鐨勬儏鍐典笅錛岀悊璁轟笂灝卞簲璇ユ槸varchar蹇簡銆傚洜涓簐archar闇瑕侀澶栫┖闂村瓨鏀懼潡闀垮害錛屾墍浠ュ彧瑕乴ength(1-fillfactor)澶т簬榪欎釜瀛樻斁絀洪棿錛堝ソ鍍忔槸2瀛楄妭)錛岄偅涔堝畠?yōu)兗?xì)姣旂浉鍚岄暱搴︾殑char蹇簡銆?<br /> <br /> 13銆乶varchar姣攙archar瑕佹參涓婁竴浜涳紝鑰屼笖瀵逛簬闈瀠nicode瀛楃瀹冧細(xì)鍗犵敤鍙屽嶇殑絀洪棿錛岄偅涔堣繖涔堜竴縐嶇被鍨嬫帹鍑烘潵鏄負(fù)浠涔堝憿錛熷錛屽氨鏄負(fù)浜嗗浗闄呭寲錛屽浜巙nicode綾誨瀷鐨勬暟鎹紝鎺掑簭瑙勫垯瀵瑰畠浠槸涓嶈搗浣滅敤鐨勶紝鑰岄潪unicode瀛楃鍦ㄥ鐞嗕笉鍚岃璦鐨勬暟鎹椂錛屽繀欏繪寚瀹氭帓搴忚鍒欐墠鑳芥甯稿伐浣滐紝鎵浠綾誨瀷灝辮繖涔堜竴鐐瑰ソ澶勩?<br /> <br /> <br /> 鎬葷粨闄堣瘝錛?<br /> 1銆佸鏋滄暟鎹噺闈炲父澶э紝鍙堣兘100%紜畾闀垮害涓斾繚瀛樺彧鏄痑nsi瀛楃錛岄偅涔坈har <br /> 2銆佽兘紜畾闀垮害鍙堜笉涓瀹氭槸ansi瀛楃鎴栬咃紝閭ｄ箞鐢╪char錛?<br /> 3銆佷笉紜畾闀垮害錛岃鏌ヨ涓斿笇鏈涘埄鐢ㄧ儲寮曠殑璇濓紝鐢╪varchar綾誨瀷鍚э紝灝嗗畠浠鍒?00錛?<br /> 4銆佷笉鏌ヨ鐨勮瘽娌′粈涔堝ソ璇寸殑錛岀敤nvarchar(4000) <br /> 5銆佹ф牸璞埥鐨勫彲浠ュ彧鐢?鍜?錛屽伓灝?dāng)鐢ㄧ?錛屾瘯绔熻繖鏄竴縐嶉澶栬鏄庯紝絳変簬鍛婅瘔鍒漢璇達(dá)紝鎴戜竴瀹氶渶瑕侀暱搴︿負(fù)X浣嶇殑鏁版嵁 <br /> <br /> 榪欐牱涓鏉ワ紝鐢熸椿鏄笉鏄彉鎴愮編濂藉浜嗭紵銆濡傛灉榪樻湁娌℃槑鐧界殑錛岄偅涔堣繕鏄渷鐐歸挶鍘諱拱钀濆崪鍚с? 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