3 comments

  • vfp 数据库集: 巨量存放,仍然非常快速之体会
    (1)目前,对于所有的数据库,个人认为:从操作类型方面。可以分为2类。文件型数据库和服务型数据库。
    前者有 access 和 vfp 数据库等,文件型磁盘存放,无平台直接使用。后者有 sql_server 和 oracle 等,基本上都借助平台
    才能使用。目前常见的的使用中,前者侧重于小型局域网或单机,后者侧重于大型网络或远程服务。因为两者用途各有侧重,
    所以,各自表现的性能和主要功能互不兼顾。前者操作简单容易,运行速度快,而且很容易移植和修改。
    其中,vfp 数据库的特征更为突出。他不但运行速度更快,而且单表的容纳量大于 access. 因为他是受vfp直接操纵,
    在众多数据库中是唯一的不需要做数据库连接,也能直通直打、直接操作的数据库。到目前为止,极易操作的性能,
    在各类数据库中仍然属于第一。服务型数据库特点,容量大,共享性能高,端口连接保密性强。所以适合用于
    大型网络和远程。但是,具体使用时,不能直通直打,必须作有效连接,利用较为严格的 sql 查询语句才能实现其功能,
    相对的,跨数据库查询难度大,速度慢。
    (2)从数据库表的容量使用特点,所有的数据库中的表也可以分为2类。有限型表和无限型表两类,这是按照数据库的
    表使用时,使用者存放数据量的限度相区分,于表本身属性无关。举例说明:例如在医院his 系统中,药品目录表,
    收费项目目录表,医生名表,医院科室名称表等。这些表存放记录数,伴随时间的不断过度,实际应用中,他不会无限
    增加记录数的。总之,记录数据到达一定数量后,按照实际需要,不会再有多少记录条数继续添加,或者不再增加了。
    呈现极限状态。这个表可以称为有限型表。我们再看另一些表:门诊和住院业务记录表,物品入库或出库表等,
    这些表存放记录数,会伴随时间的不断过度,他会不断无限增加记录数的。呈现无限增长的趋势,不存在极限。
    这种表可以称为无限型表。
    (3)vfp 数据库集的侧重。关于有限型表,存放量和运行速度,一般遇不到多大困难,操作也容易掌握。
    但是,无限型表不同,当把一类数据不断的放在一张数据表内时,当数据量达到一定程度,超大量存放数据时,
    想要仍然保持快速如初的数据库操作,显然变得比较困难了。针对无限型表,数据库集开始发挥重大的作用。
    由于vfp数据库是文件型数据库,利用文件型的特点,可以在很大程度上,解决vfp数据表的巨量存放记录时,
    如何仍然快速实现数据库操作的问题。数据库集,针对的就是无限型数据表。
    (4)vfp 数据库集的结构特点。把存放同类数据的一张无限型表,分成相同结构和字段的众多的表,有序的放在
    文件夹中,文件夹也是有序的,可以层层叠加,可容纳成千上万张相同结构的表。硬盘存放文件的量本来就是巨大的。
    每张表容纳数据记录,则是相对很少的。常规情况下,数据操作只是针对记录量很少的少数张表进行,大量相同结构
    和字段的表,暂时都属于无关的表不需要操作。针对性的操作,使得操作速度大大加强。这个存放大量相同结构
    和字段的文件型数据库的文件夹,就是一个数据库集。
    数据库集,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,文件夹内又有文件夹,层层叠加,
    最后的底层文件夹才包含同字段的大量文件型数据库和表。这是一个多么庞大的数据库!简直可以用阶乘计算!
    数据的存放、查询、交换,在大量的同字段的库表中,只对相关的极少数文件夹内数据库进行,好比在图书馆内,
    查找与存放书籍资料,按照自然法则,当然是,房间内全部图书的类型尽量相近,同书架的书籍进一步相近,
    同层书籍更加相近..,步步逼近,同者相邻。我们存放资料,不可能把极其大量的全部相近的资料,都放在一本书内,
    更不可能把它放在一本书的一个页面内,让这一页的纸张变得非常非常的长。数据库集的存放和查询模式,
    是个同构同字段多表的集合,数据存放和查询,是地址有序的分散和集中的调合,符合自然常规法则规律。
    (5)vfp数据库集的可扩充性。他是很容易扩充的,可以自动或人工方式,直接复制空库,就立刻增多数据库
    的个数。只要硬盘空间容量允许,他可以一直复制下去。呈现名副其实的海量存放。同时,数据在执行存放时,
    可以做到不同磁盘的同时多份存放。因此,这种数据库一般不需要人工备份,处理得当会确保数据永远不会丢失。
    因为常规情况下,多微机多磁盘同时损坏几乎是不可能的。
    (6)数据库集的分类。
    (a)时间序列型。这是按照一定时间内设计出一张表。比如每天一张同结构表。天天自动更换新表操作。
    主要侧重于,顺序时间内,定期时间内,发生的全部数据的操作。比如:2010年2月16日的仓库物品出库记录表。
    可以是:\\..\e$\y2010\m02\wpck!wpck_16,他只存放该天的有关全部数据。
    (b)数字序列型。这是按照数字排列构造的表。主要侧重于不定时间内,产生数据的操作。比如:医院的一个病员,
    自来院就诊,直至现在的全部诊断,检查、治疗、用药方案的全部数据。由于他何时来医院,何时再来?是个不定数,
    但是,他的门诊号是:000051067,那么,这张表可以是:\\..\e$005\10\br_67.独立存放本人的全部资料。
    而对于门诊号总表,即存放全部门诊号的目录表,记录不重复。可以做成数据库集。而该库集的引导表,则几乎是一个
    有限型表,只记载区段。
    (c)混合型。这是时间型和数字型表的混合使用。其中,时间型文件夹内,可能存在数字型文件夹,或者相互
    掺杂。这要根据实际需要而设计。
    (7) vfp数据库集的运行的特点。他运行的最大特点就是:以“寻址方式”为主。操作数据的时候,首先寻找的
    是数据库的位址。系统存放数据时,能够自动识别,哪些数据应该放在哪些数据库类之中。查询时,只需寻找出这些
    数据库表,所需数据肯定就在里面,而其他的同结构数据库里根本就没有,一概不需要操作,就可以了。
    常规情况下,实现数据库集内的各种各样的数据操作,通常只是对其中一张表的操作,而且这张表内的
    数据又是相对的那么少!或者对多张类似表的重复式操作。操作他,如同操作单张表一样简单。数据的存放和
    修改一般只对单张或2-3张小表进行,因而快速完成。而数据查询,是写在数据库里面的固定存储过程。调用数据库集,
    如同调用一张单表。巨量数据汇总时,存储过程实现一边读数,同时汇总的功能。流水作业式,
    中间不会产生巨量的临时表。常规情况下,数据库集里面的全部数据,绝大部分是长期处于非活动状态,不被操作。
    这一点,是与大型数据库 sql_server 或 oracle,在使用少量表做巨量存储时存在的原则区别。后者正好是相反的。
    例如:数据装入:记录每天门诊业务,每天自动打开时间型库集的2张新空白表,其中还有1张备份。
    同步分次方式装入该天的全部记录。 例如:查询2010年1月1日–月底的药品出库明细。寻址查找时间型库集,
    抽出该月1-31的表,依次合并即可。查询该月内药品明细汇总,再加一条 select .. group by 语句。最快的,
    查询某一天的明细,直接抽出这张表即可。因为数据存放时,提前已经按需要分类存放,查询时,又容易又快。
    (8)vfp数据库集,存量与速度的关系。伴随整个库集的记录数量的增加,查询速度影响不大。
    因为其中很多操作方式,其操作速度与整个库集的存放量无关。当整个库集的存储数据的总量远远超过sql_server
    或 oracle时,与后者比较,他仍然呈现着极其快速的运行模式现象。原因是,他一直在一个或一些小表上运行。
    一直是依靠“寻址方式”进行数据操作。大家都知道,目前微机的寻址功能,到底有多块!是不言而喻的!
    假如,在海量的一张大表中,搜索寻找符合条件的记录的操作。后者无疑是,数据越来越多时,
    无关数据作为一种累加的包袱共同参与运行之中。这个缺陷,在大型数据库里,比如:oracle中尤为突出。
    而vfp数据库集没有这个包袱,无关的数据表他会自动不再访问的,因为他的查询方式,是以“寻找地址”为重点,
    而不是”大表内找记录“方式。
    (7)vfp数据库集与服务型数据库的联合使用。因为两者各有优势侧重,在远程大型网络中,使用大型数据库,用于
    数据的接受和发送,而数据的备份存放和查询,则使用vfp数据库集。笔者的实际应用中,是让大型数据库的某些频繁
    应用,交换量最多的数据库表,时刻恢复到空记录状态。可以让程序自动实现两种数据库之间的数据交换,
    起到各取优势的作用。当然,这里面也要牵扯到很多问题,可以因事而定,灵活处理。..可待续..

    欢迎高手多加指点! 信箱: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

  • 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

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I'm the co-host of HubShots and the CEO of XEN - helping mid-large B2B companies with their digital marketing and lead generation.

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