Milind’s February letter points us to the latest Sedna CTP release
You beauty! Just in time for OzFox. I wonder if I can get this onto all the conference memory sticks in time…
The most interesting part of the release is the new Vista common dialogs – can’t wait to see it in action (attention: plug for OzFox keynote in progress :-)
vfp æ•°æ®åº“集: å·¨é‡å˜æ”¾ï¼Œä»ç„¶éžå¸¸å¿«é€Ÿä¹‹ä½“会
(1)目å‰ï¼Œå¯¹äºŽæ‰€æœ‰çš„æ•°æ®åº“,个人认为:从æ“作类型方é¢ã€‚å¯ä»¥åˆ†ä¸º2类。文件型数æ®åº“å’ŒæœåŠ¡åž‹æ•°æ®åº“。
å‰è€…有 access å’Œ vfp æ•°æ®åº“ç‰ï¼Œæ–‡ä»¶åž‹ç£ç›˜å˜æ”¾ï¼Œæ— å¹³å°ç›´æŽ¥ä½¿ç”¨ã€‚åŽè€…有 sql_server å’Œ oracle ç‰ï¼ŒåŸºæœ¬ä¸Šéƒ½å€ŸåŠ©å¹³å°
æ‰èƒ½ä½¿ç”¨ã€‚ç›®å‰å¸¸è§çš„的使用ä¸ï¼Œå‰è€…侧é‡äºŽå°åž‹å±€åŸŸç½‘或å•æœºï¼ŒåŽè€…侧é‡äºŽå¤§åž‹ç½‘络或远程æœåŠ¡ã€‚å› ä¸ºä¸¤è€…ç”¨é€”å„有侧é‡ï¼Œ
所以,å„自表现的性能和主è¦åŠŸèƒ½äº’ä¸å…¼é¡¾ã€‚å‰è€…æ“作简å•å®¹æ˜“,è¿è¡Œé€Ÿåº¦å¿«ï¼Œè€Œä¸”很容易移æ¤å’Œä¿®æ”¹ã€‚
å…¶ä¸ï¼Œvfp æ•°æ®åº“的特å¾æ›´ä¸ºçªå‡ºã€‚ä»–ä¸ä½†è¿è¡Œé€Ÿåº¦æ›´å¿«ï¼Œè€Œä¸”å•è¡¨çš„容纳é‡å¤§äºŽ access. å› ä¸ºä»–æ˜¯å—vfp直接æ“纵,
在众多数æ®åº“ä¸æ˜¯å”¯ä¸€çš„ä¸éœ€è¦åšæ•°æ®åº“连接,也能直通直打ã€ç›´æŽ¥æ“作的数æ®åº“。到目å‰ä¸ºæ¢ï¼Œæžæ˜“æ“作的性能,
在å„类数æ®åº“ä¸ä»ç„¶å±žäºŽç¬¬ä¸€ã€‚æœåŠ¡åž‹æ•°æ®åº“特点,容é‡å¤§ï¼Œå…±äº«æ€§èƒ½é«˜ï¼Œç«¯å£è¿žæŽ¥ä¿å¯†æ€§å¼ºã€‚所以适åˆç”¨äºŽ
大型网络和远程。但是,具体使用时,ä¸èƒ½ç›´é€šç›´æ‰“ï¼Œå¿…é¡»ä½œæœ‰æ•ˆè¿žæŽ¥ï¼Œåˆ©ç”¨è¾ƒä¸ºä¸¥æ ¼çš„ sql 查询è¯å¥æ‰èƒ½å®žçŽ°å…¶åŠŸèƒ½ï¼Œ
相对的,跨数æ®åº“查询难度大,速度慢。
(2)从数æ®åº“表的容é‡ä½¿ç”¨ç‰¹ç‚¹ï¼Œæ‰€æœ‰çš„æ•°æ®åº“ä¸çš„表也å¯ä»¥åˆ†ä¸º2类。有é™åž‹è¡¨å’Œæ— é™åž‹è¡¨ä¸¤ç±»ï¼Œè¿™æ˜¯æŒ‰ç…§æ•°æ®åº“çš„
表使用时,使用者å˜æ”¾æ•°æ®é‡çš„é™åº¦ç›¸åŒºåˆ†ï¼ŒäºŽè¡¨æœ¬èº«å±žæ€§æ— 关。举例说明:例如在医院his 系统ä¸ï¼Œè¯å“目录表,
收费项目目录表,医生å表,医院科室å称表ç‰ã€‚这些表å˜æ”¾è®°å½•æ•°ï¼Œä¼´éšæ—¶é—´çš„ä¸æ–过度,实际应用ä¸ï¼Œä»–ä¸ä¼šæ— é™
å¢žåŠ è®°å½•æ•°çš„ã€‚æ€»ä¹‹ï¼Œè®°å½•æ•°æ®åˆ°è¾¾ä¸€å®šæ•°é‡åŽï¼ŒæŒ‰ç…§å®žé™…需è¦ï¼Œä¸ä¼šå†æœ‰å¤šå°‘记录æ¡æ•°ç»§ç»æ·»åŠ ,或者ä¸å†å¢žåŠ 了。
呈现æžé™çŠ¶æ€ã€‚这个表å¯ä»¥ç§°ä¸ºæœ‰é™åž‹è¡¨ã€‚我们å†çœ‹å¦ä¸€äº›è¡¨ï¼šé—¨è¯Šå’Œä½é™¢ä¸šåŠ¡è®°å½•è¡¨ï¼Œç‰©å“入库或出库表ç‰ï¼Œ
这些表å˜æ”¾è®°å½•æ•°ï¼Œä¼šä¼´éšæ—¶é—´çš„ä¸æ–过度,他会ä¸æ–æ— é™å¢žåŠ è®°å½•æ•°çš„ã€‚å‘ˆçŽ°æ— é™å¢žé•¿çš„趋势,ä¸å˜åœ¨æžé™ã€‚
è¿™ç§è¡¨å¯ä»¥ç§°ä¸ºæ— é™åž‹è¡¨ã€‚
(3)vfp æ•°æ®åº“集的侧é‡ã€‚关于有é™åž‹è¡¨ï¼Œå˜æ”¾é‡å’Œè¿è¡Œé€Ÿåº¦ï¼Œä¸€èˆ¬é‡ä¸åˆ°å¤šå¤§å›°éš¾ï¼Œæ“作也容易掌æ¡ã€‚
ä½†æ˜¯ï¼Œæ— é™åž‹è¡¨ä¸åŒï¼Œå½“把一类数æ®ä¸æ–çš„æ”¾åœ¨ä¸€å¼ æ•°æ®è¡¨å†…时,当数æ®é‡è¾¾åˆ°ä¸€å®šç¨‹åº¦ï¼Œè¶…大é‡å˜æ”¾æ•°æ®æ—¶ï¼Œ
想è¦ä»ç„¶ä¿æŒå¿«é€Ÿå¦‚åˆçš„æ•°æ®åº“æ“作,显然å˜å¾—æ¯”è¾ƒå›°éš¾äº†ã€‚é’ˆå¯¹æ— é™åž‹è¡¨ï¼Œæ•°æ®åº“集开始å‘挥é‡å¤§çš„作用。
由于vfpæ•°æ®åº“是文件型数æ®åº“,利用文件型的特点,å¯ä»¥åœ¨å¾ˆå¤§ç¨‹åº¦ä¸Šï¼Œè§£å†³vfpæ•°æ®è¡¨çš„å·¨é‡å˜æ”¾è®°å½•æ—¶ï¼Œ
如何ä»ç„¶å¿«é€Ÿå®žçŽ°æ•°æ®åº“æ“作的问题。数æ®åº“é›†ï¼Œé’ˆå¯¹çš„å°±æ˜¯æ— é™åž‹æ•°æ®è¡¨ã€‚
(4)vfp æ•°æ®åº“集的结构特点。把å˜æ”¾åŒç±»æ•°æ®çš„ä¸€å¼ æ— é™åž‹è¡¨ï¼Œåˆ†æˆç›¸åŒç»“æž„å’Œå—段的众多的表,有åºçš„放在
文件夹ä¸ï¼Œæ–‡ä»¶å¤¹ä¹Ÿæ˜¯æœ‰åºçš„,å¯ä»¥å±‚层å åŠ ï¼Œå¯å®¹çº³æˆåƒä¸Šä¸‡å¼ 相åŒç»“构的表。硬盘å˜æ”¾æ–‡ä»¶çš„é‡æœ¬æ¥å°±æ˜¯å·¨å¤§çš„。
æ¯å¼ 表容纳数æ®è®°å½•ï¼Œåˆ™æ˜¯ç›¸å¯¹å¾ˆå°‘的。常规情况下,数æ®æ“作åªæ˜¯é’ˆå¯¹è®°å½•é‡å¾ˆå°‘çš„å°‘æ•°å¼ è¡¨è¿›è¡Œï¼Œå¤§é‡ç›¸åŒç»“æž„
å’Œå—æ®µçš„è¡¨ï¼Œæš‚æ—¶éƒ½å±žäºŽæ— å…³çš„è¡¨ä¸éœ€è¦æ“作。针对性的æ“作,使得æ“ä½œé€Ÿåº¦å¤§å¤§åŠ å¼ºã€‚è¿™ä¸ªå˜æ”¾å¤§é‡ç›¸åŒç»“æž„
å’Œå—段的文件型数æ®åº“的文件夹,就是一个数æ®åº“集。
æ•°æ®åº“集,好比是一个庞大的图书馆,内部的书架好比是一个个文件夹,文件夹内åˆæœ‰æ–‡ä»¶å¤¹ï¼Œå±‚层å åŠ ï¼Œ
最åŽçš„底层文件夹æ‰åŒ…å«åŒå—段的大é‡æ–‡ä»¶åž‹æ•°æ®åº“和表。这是一个多么庞大的数æ®åº“ï¼ç®€ç›´å¯ä»¥ç”¨é˜¶ä¹˜è®¡ç®—ï¼
æ•°æ®çš„å˜æ”¾ã€æŸ¥è¯¢ã€äº¤æ¢ï¼Œåœ¨å¤§é‡çš„åŒå—段的库表ä¸ï¼Œåªå¯¹ç›¸å…³çš„æžå°‘数文件夹内数æ®åº“进行,好比在图书馆内,
查找与å˜æ”¾ä¹¦ç±èµ„料,按照自然法则,当然是,房间内全部图书的类型尽é‡ç›¸è¿‘,åŒä¹¦æž¶çš„书ç±è¿›ä¸€æ¥ç›¸è¿‘,
åŒå±‚书ç±æ›´åŠ 相近..,æ¥æ¥é€¼è¿‘,åŒè€…相邻。我们å˜æ”¾èµ„料,ä¸å¯èƒ½æŠŠæžå…¶å¤§é‡çš„全部相近的资料,都放在一本书内,
æ›´ä¸å¯èƒ½æŠŠå®ƒæ”¾åœ¨ä¸€æœ¬ä¹¦çš„一个页é¢å†…,è®©è¿™ä¸€é¡µçš„çº¸å¼ å˜å¾—éžå¸¸éžå¸¸çš„长。数æ®åº“集的å˜æ”¾å’ŒæŸ¥è¯¢æ¨¡å¼ï¼Œ
是个åŒæž„åŒå—段多表的集åˆï¼Œæ•°æ®å˜æ”¾å’ŒæŸ¥è¯¢ï¼Œæ˜¯åœ°å€æœ‰åºçš„分散和集ä¸çš„è°ƒåˆï¼Œç¬¦åˆè‡ªç„¶å¸¸è§„法则规律。
(5)vfpæ•°æ®åº“集的å¯æ‰©å……性。他是很容易扩充的,å¯ä»¥è‡ªåŠ¨æˆ–人工方å¼ï¼Œç›´æŽ¥å¤åˆ¶ç©ºåº“,就立刻增多数æ®åº“
的个数。åªè¦ç¡¬ç›˜ç©ºé—´å®¹é‡å…许,他å¯ä»¥ä¸€ç›´å¤åˆ¶ä¸‹åŽ»ã€‚呈现å副其实的海é‡å˜æ”¾ã€‚åŒæ—¶ï¼Œæ•°æ®åœ¨æ‰§è¡Œå˜æ”¾æ—¶ï¼Œ
å¯ä»¥åšåˆ°ä¸åŒç£ç›˜çš„åŒæ—¶å¤šä»½å˜æ”¾ã€‚å› æ¤ï¼Œè¿™ç§æ•°æ®åº“一般ä¸éœ€è¦äººå·¥å¤‡ä»½ï¼Œå¤„ç†å¾—当会确ä¿æ•°æ®æ°¸è¿œä¸ä¼šä¸¢å¤±ã€‚
å› ä¸ºå¸¸è§„æƒ…å†µä¸‹ï¼Œå¤šå¾®æœºå¤šç£ç›˜åŒæ—¶æŸåå‡ ä¹Žæ˜¯ä¸å¯èƒ½çš„。
(6)数æ®åº“集的分类。
(a)时间åºåˆ—åž‹ã€‚è¿™æ˜¯æŒ‰ç…§ä¸€å®šæ—¶é—´å†…è®¾è®¡å‡ºä¸€å¼ è¡¨ã€‚æ¯”å¦‚æ¯å¤©ä¸€å¼ åŒç»“构表。天天自动更æ¢æ–°è¡¨æ“作。
主è¦ä¾§é‡äºŽï¼Œé¡ºåºæ—¶é—´å†…,定期时间内,å‘生的全部数æ®çš„æ“作。比如:2010å¹´2月16日的仓库物å“出库记录表。
å¯ä»¥æ˜¯ï¼š\\..\e$\y2010\m02\wpck!wpck_16,他åªå˜æ”¾è¯¥å¤©çš„有关全部数æ®ã€‚
(b)数å—åºåˆ—型。这是按照数å—æŽ’åˆ—æž„é€ çš„è¡¨ã€‚ä¸»è¦ä¾§é‡äºŽä¸å®šæ—¶é—´å†…,产生数æ®çš„æ“作。比如:医院的一个病员,
自æ¥é™¢å°±è¯Šï¼Œç›´è‡³çŽ°åœ¨çš„全部诊æ–,检查ã€æ²»ç–—ã€ç”¨è¯æ–¹æ¡ˆçš„全部数æ®ã€‚由于他何时æ¥åŒ»é™¢,何时å†æ¥ï¼Ÿæ˜¯ä¸ªä¸å®šæ•°ï¼Œ
但是,他的门诊å·æ˜¯ï¼š000051067ï¼Œé‚£ä¹ˆï¼Œè¿™å¼ è¡¨å¯ä»¥æ˜¯ï¼š\\..\e$005\10\br_67.独立å˜æ”¾æœ¬äººçš„全部资料。
而对于门诊å·æ€»è¡¨ï¼Œå³å˜æ”¾å…¨éƒ¨é—¨è¯Šå·çš„目录表,记录ä¸é‡å¤ã€‚å¯ä»¥åšæˆæ•°æ®åº“é›†ã€‚è€Œè¯¥åº“é›†çš„å¼•å¯¼è¡¨ï¼Œåˆ™å‡ ä¹Žæ˜¯ä¸€ä¸ª
有é™åž‹è¡¨,åªè®°è½½åŒºæ®µã€‚
(c)混åˆåž‹ã€‚这是时间型和数å—型表的混åˆä½¿ç”¨ã€‚å…¶ä¸ï¼Œæ—¶é—´åž‹æ–‡ä»¶å¤¹å†…,å¯èƒ½å˜åœ¨æ•°å—型文件夹,或者相互
掺æ‚。这è¦æ ¹æ®å®žé™…需è¦è€Œè®¾è®¡ã€‚
(7) vfpæ•°æ®åº“集的è¿è¡Œçš„特点。他è¿è¡Œçš„最大特点就是:以“寻å€æ–¹å¼â€ä¸ºä¸»ã€‚æ“作数æ®çš„时候,首先寻找的
是数æ®åº“çš„ä½å€ã€‚系统å˜æ”¾æ•°æ®æ—¶ï¼Œèƒ½å¤Ÿè‡ªåŠ¨è¯†åˆ«ï¼Œå“ªäº›æ•°æ®åº”该放在哪些数æ®åº“类之ä¸ã€‚查询时,åªéœ€å¯»æ‰¾å‡ºè¿™äº›
æ•°æ®åº“表,所需数æ®è‚¯å®šå°±åœ¨é‡Œé¢ï¼Œè€Œå…¶ä»–çš„åŒç»“æž„æ•°æ®åº“é‡Œæ ¹æœ¬å°±æ²¡æœ‰ï¼Œä¸€æ¦‚ä¸éœ€è¦æ“作,就å¯ä»¥äº†ã€‚
常规情况下,实现数æ®åº“集内的å„ç§å„æ ·çš„æ•°æ®æ“作,通常åªæ˜¯å¯¹å…¶ä¸ä¸€å¼ 表的æ“ä½œï¼Œè€Œä¸”è¿™å¼ è¡¨å†…çš„
æ•°æ®åˆæ˜¯ç›¸å¯¹çš„那么少ï¼æˆ–è€…å¯¹å¤šå¼ ç±»ä¼¼è¡¨çš„é‡å¤å¼æ“作。æ“作他,如åŒæ“作å•å¼ è¡¨ä¸€æ ·ç®€å•ã€‚æ•°æ®çš„å˜æ”¾å’Œ
修改一般åªå¯¹å•å¼ 或2-3å¼ å°è¡¨è¿›è¡Œï¼Œå› 而快速完æˆã€‚而数æ®æŸ¥è¯¢ï¼Œæ˜¯å†™åœ¨æ•°æ®åº“里é¢çš„固定å˜å‚¨è¿‡ç¨‹ã€‚调用数æ®åº“集,
如åŒè°ƒç”¨ä¸€å¼ å•è¡¨ã€‚å·¨é‡æ•°æ®æ±‡æ€»æ—¶ï¼Œå˜å‚¨è¿‡ç¨‹å®žçŽ°ä¸€è¾¹è¯»æ•°ï¼ŒåŒæ—¶æ±‡æ€»çš„功能。æµæ°´ä½œä¸šå¼ï¼Œ
ä¸é—´ä¸ä¼šäº§ç”Ÿå·¨é‡çš„临时表。常规情况下,数æ®åº“集里é¢çš„全部数æ®ï¼Œç»å¤§éƒ¨åˆ†æ˜¯é•¿æœŸå¤„于éžæ´»åŠ¨çŠ¶æ€ï¼Œä¸è¢«æ“作。
这一点,是与大型数æ®åº“ sql_server 或 oracle,在使用少é‡è¡¨åšå·¨é‡å˜å‚¨æ—¶å˜åœ¨çš„原则区别。åŽè€…æ£å¥½æ˜¯ç›¸å的。
例如:数æ®è£…入:记录æ¯å¤©é—¨è¯Šä¸šåŠ¡ï¼Œæ¯å¤©è‡ªåŠ¨æ‰“开时间型库集的2å¼ æ–°ç©ºç™½è¡¨ï¼Œå…¶ä¸è¿˜æœ‰1å¼ å¤‡ä»½ã€‚
åŒæ¥åˆ†æ¬¡æ–¹å¼è£…入该天的全部记录。 例如:查询2010å¹´1月1æ—¥–月底的è¯å“出库明细。寻å€æŸ¥æ‰¾æ—¶é—´åž‹åº“集,
抽出该月1-31的表,ä¾æ¬¡åˆå¹¶å³å¯ã€‚查询该月内è¯å“明细汇总,å†åŠ ä¸€æ¡ select .. group by è¯å¥ã€‚最快的,
查询æŸä¸€å¤©çš„æ˜Žç»†ï¼Œç›´æŽ¥æŠ½å‡ºè¿™å¼ è¡¨å³å¯ã€‚å› ä¸ºæ•°æ®å˜æ”¾æ—¶ï¼Œæå‰å·²ç»æŒ‰éœ€è¦åˆ†ç±»å˜æ”¾ï¼ŒæŸ¥è¯¢æ—¶ï¼Œåˆå®¹æ˜“åˆå¿«ã€‚
(8)vfpæ•°æ®åº“集,å˜é‡ä¸Žé€Ÿåº¦çš„关系。伴éšæ•´ä¸ªåº“集的记录数é‡çš„å¢žåŠ ï¼ŒæŸ¥è¯¢é€Ÿåº¦å½±å“ä¸å¤§ã€‚
å› ä¸ºå…¶ä¸å¾ˆå¤šæ“作方å¼ï¼Œå…¶æ“作速度与整个库集的å˜æ”¾é‡æ— 关。当整个库集的å˜å‚¨æ•°æ®çš„总é‡è¿œè¿œè¶…过sql_server
或 oracleæ—¶,与åŽè€…比较,他ä»ç„¶å‘ˆçŽ°ç€æžå…¶å¿«é€Ÿçš„è¿è¡Œæ¨¡å¼çŽ°è±¡ã€‚åŽŸå› æ˜¯ï¼Œä»–ä¸€ç›´åœ¨ä¸€ä¸ªæˆ–ä¸€äº›å°è¡¨ä¸Šè¿è¡Œã€‚
一直是ä¾é “寻å€æ–¹å¼â€è¿›è¡Œæ•°æ®æ“作。大家都知é“,目å‰å¾®æœºçš„寻å€åŠŸèƒ½ï¼Œåˆ°åº•æœ‰å¤šå—ï¼æ˜¯ä¸è¨€è€Œå–»çš„ï¼
å‡å¦‚,在海é‡çš„ä¸€å¼ å¤§è¡¨ä¸ï¼Œæœç´¢å¯»æ‰¾ç¬¦åˆæ¡ä»¶çš„记录的æ“作。åŽè€…æ— ç–‘æ˜¯ï¼Œæ•°æ®è¶Šæ¥è¶Šå¤šæ—¶ï¼Œ
æ— å…³æ•°æ®ä½œä¸ºä¸€ç§ç´¯åŠ 的包袱共åŒå‚与è¿è¡Œä¹‹ä¸ã€‚这个缺陷,在大型数æ®åº“里,比如:oracleä¸å°¤ä¸ºçªå‡ºã€‚
而vfpæ•°æ®åº“é›†æ²¡æœ‰è¿™ä¸ªåŒ…è¢±ï¼Œæ— å…³çš„æ•°æ®è¡¨ä»–会自动ä¸å†è®¿é—®çš„ï¼Œå› ä¸ºä»–çš„æŸ¥è¯¢æ–¹å¼ï¼Œæ˜¯ä»¥â€œå¯»æ‰¾åœ°å€”为é‡ç‚¹ï¼Œ
而ä¸æ˜¯â€å¤§è¡¨å†…找记录“方å¼ã€‚
(7)vfpæ•°æ®åº“集与æœåŠ¡åž‹æ•°æ®åº“çš„è”åˆä½¿ç”¨ã€‚å› ä¸ºä¸¤è€…å„有优势侧é‡ï¼Œåœ¨è¿œç¨‹å¤§åž‹ç½‘络ä¸ï¼Œä½¿ç”¨å¤§åž‹æ•°æ®åº“,用于
æ•°æ®çš„接å—å’Œå‘é€ï¼Œè€Œæ•°æ®çš„备份å˜æ”¾å’ŒæŸ¥è¯¢ï¼Œåˆ™ä½¿ç”¨vfpæ•°æ®åº“集。笔者的实际应用ä¸ï¼Œæ˜¯è®©å¤§åž‹æ•°æ®åº“çš„æŸäº›é¢‘ç¹
应用,交æ¢é‡æœ€å¤šçš„æ•°æ®åº“表,时刻æ¢å¤åˆ°ç©ºè®°å½•çŠ¶æ€ã€‚å¯ä»¥è®©ç¨‹åºè‡ªåŠ¨å®žçŽ°ä¸¤ç§æ•°æ®åº“之间的数æ®äº¤æ¢ï¼Œ
起到å„å–优势的作用。当然,这里é¢ä¹Ÿè¦ç‰µæ‰¯åˆ°å¾ˆå¤šé—®é¢˜ï¼Œå¯ä»¥å› 事而定,çµæ´»å¤„ç†ã€‚..å¯å¾…ç»..
æ¬¢è¿Žé«˜æ‰‹å¤šåŠ æŒ‡ç‚¹ï¼ ä¿¡ç®±ï¼šqingfameng@yahoo.cn
Thanks for the comment, even though it is hard for me to understand. I used Google translate to translate the comment into English and it did a semi-reasonable job:
http://translate.google.com/
Here it is:
vfp database set: massive storage, the experience is still very fast
(1) At present, for all databases, personal view is that: From the types of operations. Can be divided into two categories. Document-type databases, and service-oriented databases.
The former has access and the vfp database, file-based disk storage, no platform to be used directly. Latter sql_server and oracle and so on, basically the use of platform
To be used. The current common usage, the former focusing on a small local area network or stand-alone, which is focused on large-scale network or remote services. Because the two uses have different emphases,
Therefore, the performance and the performance of their main functions of each other does not take into account. The former are simple and easy to run fast, and very easy to transplant and modified.
Which, vfp database features more prominent. He not only runs faster, but the carrying capacity of more than a single table access. Because he is subject to vfp direct manipulation,
Among the many databases do not need to do is the only database connection can also be played straight through, direct operation of the database. So far, easy to operating performance,
In various databases is still a first. Service-oriented database features, large capacity, sharing high-performance, port security is strong. Therefore suitable for use
Large-scale network and remote. However, the specific use, you can not play straight through, you must be an effective link between the use of more stringent sql query in order to achieve its function,
In contrast, cross-database query is difficult, slow.
(2) from the database table using the characteristics of the capacity of all the database tables can be divided into two categories. Finite type table and the two types of infinite-type table, which is in accordance with the database
Table use, the user storage limits the amount of data to distinguish, on the table itself is irrelevant attributes. For example: for example, his system in a hospital, medicine table of contents
Table of fees and charges, the doctor watches, hospital departments such as the name of the table. These tables store the number of records, with the constant over-time, practical application, he would not be infinite
Increase the number of records. In short, the record data to reach a certain amount, follow the actual needs, there will not be the number of the number of records to continue to add, or are no longer increased.
Present limit state. This table can be called the finite type table. Let us look at some other table: outpatient and in-patient business records, tables, storage items, or a database table, etc.
These tables store the number of records will be accompanied by the constant over time, he will continue to increase indefinitely the number of records. Presents an infinite upward trend, there is no limit.
This table can be called an infinite-type table.
(3) vfp database, set focus on. With regard to finite type table, storage capacity and speed, the general never quite found a little difficulty, the operation is also easy to grasp.
However, the infinite-type form different from that, when a class data on a constant data sheet, when the volume of data reaches a certain level, ultra-large storage data,
Fast as ever you want to still maintain a database operation, apparently become more difficult. For the infinite-type table, the database collection begun to play a significant role.
As the vfp database is a file database, using documentary-type feature to a large extent, solve the vfp massive amount of data tables stored records,
How to quickly implement database operations are still problems. Database set for is the infinite-type data table.
(4) vfp set of structural features of the database. To store data in a similar infinite-type table, divided into the same structure and fields of a large number of tables, and orderly placed
Folder, the folder is ordered, can be superimposed layers, which could accommodate hundreds of thousands of Zhang same structure table. The amount of hard disk storage of documents has always been great.
To accommodate data record for each table, it is relatively small. Normal circumstances, the data manipulation is only a very small number for the records of a few tables for a large number of the same structure
And fields of the tables, temporary tables do not belong to independent operation. Targeted operations, makes the operating speed considerably strengthened. The large quantities of the same structure
And fields of the file folder database is a database set.
The database set, like a huge library, is like a bookshelf inside a folder inside the folder there are folders, layer upon layer overlay,
The bottom of the folder before the last field contains the number of documents with the database and tables. This is what a huge database! Can simply calculate factorial!
Data storage, query, exchange, in a large number of the library the same field in the table, only a very small number of relevant databases folder, just like in a library,
Find information and to keep books in accordance with the laws of nature, of course, is the type of room all the books as close as possible, with shelves of books for further similar
Is more similar books on the same floor .., step by step approximation, with those adjacent. We are the repository of information, it is impossible to all the extremely large number of similar information, are placed in a book, the
Let alone put it in a book within a page, so this page of the paper has become very, very long. Database storage and query pattern set,
Is an isomorphism with the field more than a collection of tables, data storage and query, is the address of an orderly dispersion and concentration of blending, in line with the natural laws of general laws.
(5) vfp database set scalability. He is very easy to expand, and can automatically or manually, directly copy the empty database, the database immediately increased
Number. As long as the capacity of hard disk space permits, he may have been copied down. Presents a true mass storage. At the same time, the data stored in the implementation, the
Can do more than the same time in different disk storage. Therefore, this database usually does not require manual backup, handle it properly will ensure that data is never lost.
Because normal circumstances, the multi-computer multi-disk at the same time damage is almost impossible.
(6) database set classification.
(A) time series model. This is according to a certain period of time to design a table. Example, the same day, a structure of the table. Automatic replacement of a new table every day operations.
Focused primarily on the order of time, regular time, place all the data operations. For example: February 16, 2010 article out of the warehouse database logs.
Can be: .. e $ y2010 m02 wpck! Wpck_16, he just kept on that day all the data.
(B) the number sequence type. This is a table constructed in accordance with the number ordered. Focused primarily on indeterminate period of time, resulting in data operations. For example: the hospital a patient,
Unsolicited hospital treatment, up to now all the diagnosis, detection, treatment, medication program all the data. Because when he will come to the hospital, when another outbreak? Is an indefinite number,
However, his out-patient number is: 000,051,067, then this table can be: .. e $ 005 10 br_67. I kept all the information independently.
As for the out-patient number matrix, that is, all the out-patient number stored table of contents, records of non-repetition. Can be made into a database set. And the library set to guide the table, it is almost a
Finite type table, only the records section.
(C) mixed type. This is the time to type and digital-type meter mixed use. Among them, the time-based folder, there may be digital-type folder, or each other
Doping. This should be designed according to actual needs.
(7) vfp database, set to run features. He runs the biggest characteristic is: to “addressing modes” as his main. Operation of the data, the first search
Is the database address. Data stored on the system can automatically identify what data should be placed in which classes into the database. Query, only to find out these
Database table, the required data definitely on the inside, while the other on the same structure of the database simply not be upheld without operation on it.
Normal circumstances, the realization of the database within a variety of data collection operations, usually only one of which the operation of the table, but within this table
The data is relatively so few! Or to more than one repetition of a similar sheet-type operations. Operation him, as simple as operating leaflets table. Data storage and
Changes in general only 2-3 pairs of leaflets or Zhang tables, so quickly. The data query is written in the database inside a fixed stored procedures. Call a database set,
Like calling a single table. Massive data aggregation, the stored procedure to achieve the side of reading, while aggregate functions. Assembly-line style,
Intermediate does not produce a huge amount of temporary tables. Normal circumstances, all the data inside the database collection, most of the long-term inactive, not to be operating.
This is associated with large databases sql_server or oracle, using a small table to do that existed when the principle of storing massive difference. The latter is precisely the opposite.
For example: the data load: Record daily out-patient services, time of day, type libraries open automatically sets two new blank sheet, in which there is a backup.
Fractionated into synchronous mode all the records that day. For example: Query January 1, 2010 – at the end of the drug out of library details. Addressing the time-based database to find set,
1-31 months out of the table, followed by the merger can be. Search the month summary of drug details, plus a select .. group by statement. Fastest
Check details of a day, directly out of this table can be. Because the data is stored, the advance has been classified according to need storage, query, quick and easy.
(8) vfp database, set the relationship between the stock and speed. With the entire library collection, the increase in the number of records, query speed much.
Since many of them operating mode, the operating speed and the entire library collection, storage capacity has nothing to do. When the whole library collection, the amount of stored data far exceeded the sql_server
Or oracle when compared with the latter, he still presents an extremely fast operating mode phenomenon. The reason is that he has some small tables in one or more runs.
Has been a reliance on “addressing mode” for data manipulation. We all know that addressing the current computer functions, in the end a number of pieces! Is self-evident!
If, in the mass of a large table, the search for records of eligible operations. The latter is, data rises, the
Irrelevant data as a cumulative burden to participate in running. This defect, in a large database, for example: oracle is particularly prominent.
The vfp database set do not have this burden, regardless of the data sheet that he would automatically cease to visit, because of his ways to search is based on “Find Address” as the focus,
Rather than the “big table to find records” approach.
(7) vfp database set and the joint use of service-oriented databases. Because both have their own merits emphasis, in the remote large-scale networks, the use of large databases, for
Receiving and sending data, while data backup storage and query, use the vfp database set. The author’s practical application is to enable a large database of some frequent
Application, exchange capacity up to a database table, always return to an empty record status. Program can automatically exchange data between the two kinds of databases,
Play depicting the role of advantage. Of course, this also involves a lot of problems inside, they could do, depending on flexibility. Can be continued .. ..
Welcome to master more pointing! E-mail: qingfameng@yahoo.cn
Thanks for the comment, even though it is hard for me to understand. I used Google translate to translate the comment into English and it did a semi-reasonable job:
http://translate.google.com/
Here it is:
vfp database set: massive storage, the experience is still very fast
(1) At present, for all databases, personal view is that: From the types of operations. Can be divided into two categories. Document-type databases, and service-oriented databases.
The former has access and the vfp database, file-based disk storage, no platform to be used directly. Latter sql_server and oracle and so on, basically the use of platform
To be used. The current common usage, the former focusing on a small local area network or stand-alone, which is focused on large-scale network or remote services. Because the two uses have different emphases,
Therefore, the performance and the performance of their main functions of each other does not take into account. The former are simple and easy to run fast, and very easy to transplant and modified.
Which, vfp database features more prominent. He not only runs faster, but the carrying capacity of more than a single table access. Because he is subject to vfp direct manipulation,
Among the many databases do not need to do is the only database connection can also be played straight through, direct operation of the database. So far, easy to operating performance,
In various databases is still a first. Service-oriented database features, large capacity, sharing high-performance, port security is strong. Therefore suitable for use
Large-scale network and remote. However, the specific use, you can not play straight through, you must be an effective link between the use of more stringent sql query in order to achieve its function,
In contrast, cross-database query is difficult, slow.
(2) from the database table using the characteristics of the capacity of all the database tables can be divided into two categories. Finite type table and the two types of infinite-type table, which is in accordance with the database
Table use, the user storage limits the amount of data to distinguish, on the table itself is irrelevant attributes. For example: for example, his system in a hospital, medicine table of contents
Table of fees and charges, the doctor watches, hospital departments such as the name of the table. These tables store the number of records, with the constant over-time, practical application, he would not be infinite
Increase the number of records. In short, the record data to reach a certain amount, follow the actual needs, there will not be the number of the number of records to continue to add, or are no longer increased.
Present limit state. This table can be called the finite type table. Let us look at some other table: outpatient and in-patient business records, tables, storage items, or a database table, etc.
These tables store the number of records will be accompanied by the constant over time, he will continue to increase indefinitely the number of records. Presents an infinite upward trend, there is no limit.
This table can be called an infinite-type table.
(3) vfp database, set focus on. With regard to finite type table, storage capacity and speed, the general never quite found a little difficulty, the operation is also easy to grasp.
However, the infinite-type form different from that, when a class data on a constant data sheet, when the volume of data reaches a certain level, ultra-large storage data,
Fast as ever you want to still maintain a database operation, apparently become more difficult. For the infinite-type table, the database collection begun to play a significant role.
As the vfp database is a file database, using documentary-type feature to a large extent, solve the vfp massive amount of data tables stored records,
How to quickly implement database operations are still problems. Database set for is the infinite-type data table.
(4) vfp set of structural features of the database. To store data in a similar infinite-type table, divided into the same structure and fields of a large number of tables, and orderly placed
Folder, the folder is ordered, can be superimposed layers, which could accommodate hundreds of thousands of Zhang same structure table. The amount of hard disk storage of documents has always been great.
To accommodate data record for each table, it is relatively small. Normal circumstances, the data manipulation is only a very small number for the records of a few tables for a large number of the same structure
And fields of the tables, temporary tables do not belong to independent operation. Targeted operations, makes the operating speed considerably strengthened. The large quantities of the same structure
And fields of the file folder database is a database set.
The database set, like a huge library, is like a bookshelf inside a folder inside the folder there are folders, layer upon layer overlay,
The bottom of the folder before the last field contains the number of documents with the database and tables. This is what a huge database! Can simply calculate factorial!
Data storage, query, exchange, in a large number of the library the same field in the table, only a very small number of relevant databases folder, just like in a library,
Find information and to keep books in accordance with the laws of nature, of course, is the type of room all the books as close as possible, with shelves of books for further similar
Is more similar books on the same floor .., step by step approximation, with those adjacent. We are the repository of information, it is impossible to all the extremely large number of similar information, are placed in a book, the
Let alone put it in a book within a page, so this page of the paper has become very, very long. Database storage and query pattern set,
Is an isomorphism with the field more than a collection of tables, data storage and query, is the address of an orderly dispersion and concentration of blending, in line with the natural laws of general laws.
(5) vfp database set scalability. He is very easy to expand, and can automatically or manually, directly copy the empty database, the database immediately increased
Number. As long as the capacity of hard disk space permits, he may have been copied down. Presents a true mass storage. At the same time, the data stored in the implementation, the
Can do more than the same time in different disk storage. Therefore, this database usually does not require manual backup, handle it properly will ensure that data is never lost.
Because normal circumstances, the multi-computer multi-disk at the same time damage is almost impossible.
(6) database set classification.
(A) time series model. This is according to a certain period of time to design a table. Example, the same day, a structure of the table. Automatic replacement of a new table every day operations.
Focused primarily on the order of time, regular time, place all the data operations. For example: February 16, 2010 article out of the warehouse database logs.
Can be: \ \ .. \ e $ \ y2010 \ m02 \ wpck! Wpck_16, he just kept on that day all the data.
(B) the number sequence type. This is a table constructed in accordance with the number ordered. Focused primarily on indeterminate period of time, resulting in data operations. For example: the hospital a patient,
Unsolicited hospital treatment, up to now all the diagnosis, detection, treatment, medication program all the data. Because when he will come to the hospital, when another outbreak? Is an indefinite number,
However, his out-patient number is: 000,051,067, then this table can be: \ \ .. \ e $ 005 \ 10 \ br_67. I kept all the information independently.
As for the out-patient number matrix, that is, all the out-patient number stored table of contents, records of non-repetition. Can be made into a database set. And the library set to guide the table, it is almost a
Finite type table, only the records section.
(C) mixed type. This is the time to type and digital-type meter mixed use. Among them, the time-based folder, there may be digital-type folder, or each other
Doping. This should be designed according to actual needs.
(7) vfp database, set to run features. He runs the biggest characteristic is: to “addressing modes” as his main. Operation of the data, the first search
Is the database address. Data stored on the system can automatically identify what data should be placed in which classes into the database. Query, only to find out these
Database table, the required data definitely on the inside, while the other on the same structure of the database simply not be upheld without operation on it.
Normal circumstances, the realization of the database within a variety of data collection operations, usually only one of which the operation of the table, but within this table
The data is relatively so few! Or to more than one repetition of a similar sheet-type operations. Operation him, as simple as operating leaflets table. Data storage and
Changes in general only 2-3 pairs of leaflets or Zhang tables, so quickly. The data query is written in the database inside a fixed stored procedures. Call a database set,
Like calling a single table. Massive data aggregation, the stored procedure to achieve the side of reading, while aggregate functions. Assembly-line style,
Intermediate does not produce a huge amount of temporary tables. Normal circumstances, all the data inside the database collection, most of the long-term inactive, not to be operating.
This is associated with large databases sql_server or oracle, using a small table to do that existed when the principle of storing massive difference. The latter is precisely the opposite.
For example: the data load: Record daily out-patient services, time of day, type libraries open automatically sets two new blank sheet, in which there is a backup.
Fractionated into synchronous mode all the records that day. For example: Query January 1, 2010 – at the end of the drug out of library details. Addressing the time-based database to find set,
1-31 months out of the table, followed by the merger can be. Search the month summary of drug details, plus a select .. group by statement. Fastest
Check details of a day, directly out of this table can be. Because the data is stored, the advance has been classified according to need storage, query, quick and easy.
(8) vfp database, set the relationship between the stock and speed. With the entire library collection, the increase in the number of records, query speed much.
Since many of them operating mode, the operating speed and the entire library collection, storage capacity has nothing to do. When the whole library collection, the amount of stored data far exceeded the sql_server
Or oracle when compared with the latter, he still presents an extremely fast operating mode phenomenon. The reason is that he has some small tables in one or more runs.
Has been a reliance on “addressing mode” for data manipulation. We all know that addressing the current computer functions, in the end a number of pieces! Is self-evident!
If, in the mass of a large table, the search for records of eligible operations. The latter is, data rises, the
Irrelevant data as a cumulative burden to participate in running. This defect, in a large database, for example: oracle is particularly prominent.
The vfp database set do not have this burden, regardless of the data sheet that he would automatically cease to visit, because of his ways to search is based on “Find Address” as the focus,
Rather than the “big table to find records” approach.
(7) vfp database set and the joint use of service-oriented databases. Because both have their own merits emphasis, in the remote large-scale networks, the use of large databases, for
Receiving and sending data, while data backup storage and query, use the vfp database set. The author’s practical application is to enable a large database of some frequent
Application, exchange capacity up to a database table, always return to an empty record status. Program can automatically exchange data between the two kinds of databases,
Play depicting the role of advantage. Of course, this also involves a lot of problems inside, they could do, depending on flexibility. Can be continued .. ..
Welcome to master more pointing! E-mail: qingfameng@yahoo.cn