(Reprint) database design guidelines —- Part 1 – before the database design

  If the enterprise data needed to compare the blood of life, then the design of the database application is the most important part.    The database design of the voluminous material, university degree courses, there are specialized on.    However, as we have repeatedly emphasized, even the best teachers but also experience than the teachings.    Therefore, we find a more recent design of the database quite accomplished professionals to teach you some of the database design skills and experience.    Our editorial from the feedback received by the 130 selected one of the 60 best skills, and these skills to prepare a paper, in order to facilitate indexing their content is divided into five parts: 
  Part 1 – before this part of the design database listed 12 basic skills, including naming norms and clear business needs. 
  Part 2 – Database table a total of 24 guidelines of skills, table covers fields of design and should avoid common problems. 
  Part 3 – select key is how the selection keys »    There are 10 specialized skills involved in system-generated primary key to the correct usage, and when and how to get the best field index performance. 
  Part 4 – ensure data integrity of the database discussed how to maintain a clear and strong, how to reduce harmful to the minimum level of data. 
  Section 5 – all kinds of tips not included in the above four parts in other skills, variety, they hope you have a database development work will be more relaxed some. 
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  Part 1 – before the database design 
  1. Inspected the existing environment in the design of a new database, you should not only carefully studied business needs but also to study the existing system.    Most of the database project is not built from scratch; Usually, the Federation of existing institutions to meet the specific needs of the existing system (which may not automatic).    It is clear that the existing system is not perfect, otherwise you would not have to re-establish a new system.    But the old system allows you to study found that some may overlook minor problems.    In general, the existing inspection system is good for you. 
  — Lamont Adams 
  I have been taken over for a regional transportation projects to develop the database, it is not difficult to live, using the Access database.    I set up a number of project design parameters, but also with customers one pair of these parameters were assessed prior view of the development environment is also under taken by the work mode, wait until the last deployment of the time, only a few terminals on the prompt and then Qiao Bianzi immediately in front of me!    Zhuaernaosai the disruption a few hours before I realized that this company's original network Paozhao two database applications, 
  And network access need to be clear and strict user account and access.    Understand this point, the problem solved: Just use the system to customers.    This project gave me the lesson is: Remember, if you like Access or Interbase such public application development environment, we must start with the surface you find out in depth within the system facing the environment in the end is how the case. 
  — Kg 
  2. The standard definition of the object named definition of norms must standardize the naming of database objects.    The database table, from the beginning of a project to determine table is a singular or plural form.    In addition to the table but also the definition of simple alias rules (for example, if the table is a word, alias on the word from the former four letters if the table is two words, two words Gequ on the first two letters Composed of four letters long alias; name from the table if the three-word, you may wish to start from the two words in a Gequ last words and then took out a further two letters, or the results of four letters long Aliases, followed by the remaining analogy) on the work table, the table can add the prefix 
  WORK_ use of the table appended to the application's name.    Shown in the table to address the use of a set of key design rules.    For example, 
  If the key is the type of figures, you can use as a suffix _ NO If it is the type of characters can be used _ CODE suffix.    The list should use the standard prefixes and suffixes.    Again, if you have a lot of the table "money" field, you may wish to add a column for each suffix _ AMT.    Also, to date the best out DATE_ as a name beginning. 
  — Richard 
  Examination table, and the statements of enquiries were named among the norms.    You may soon be a database of these different elements of the confusing name.    If you insist on unity in the name of these different components of the database, at least you should target those names beginning with the table, query or report, such as prefix to be distinguished. 
  — Rrydenm 
  If using a Microsoft Access, you can use qry, rpt, tbl and mod symbols to identify objects (such as 
  tbl_Employees).    I and SQL Server (or Oracle) deal with the time also used to index tbl table, but I used sp_company (now with sp_feft_) logo in storage, because in some time if I found a better approach will often save Several copies.    I realized when using SQL Server 2000 udf_ (or a similar tag), I identified a function of the preparation. 
  — Timothy J. Bruce 
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  3. Pre-planned the last century in the early 1980s, I also use the assets and accounts systems System 38 platform, then I am responsible for the design of all the date fields, so no charges in the case of any future efforts can easily handle 2000 The problem.    Many people said to me on the other to resolve this issue, because it is too troublesome to deal with the (known this in the long before the Y2K problem).    I fought back as long as the pre-planned future that will not encounter big trouble.    The results I only spent two weeks time to put all the procedures to the end.    Pre-planned because of the good, but the Y2K problem against the system down to a minimum (or even recently heard of the program to 1995 are also running in the AS/400 system, the only small problem is removed from the code Notes For the efforts). 
  — Generalist 
  4. Mode of access to data resources manual mode is seeking examples of people who can read "data resource manual mode," a book, the book by Len Silverston, WH 
  Inmon and the preparation of Kent Graziano, is a worthy have the best data modeling books.    The book includes chapters covering a wide range of data fields, such as personnel, institutions and work performance, and so on. 
  — Minstrelmike 
  5. Imagine the future, but can not forget the lessons of the past I found that asked users how to view the changing needs of the future is very useful.    This would achieve two objectives: first of all, you can clearly understand where the application design should be more flexible and how to avoid performance bottlenecks; Second, you did not know in advance the needs identified changes users will be surprised and like you . 
  — Chrisdk 
  We must remember the lessons of the past!    We should also develop their own experience through the sharing of experiences and help each other.    Even if users do not need to think what they would never support, we should also conduct their education in this regard, we have faced such a moment "Had done so Gaiduo Hao» »." 
  — Dhattrem 
  6. In practice prior to the physical design of the logic of in-depth physical design to conduct before logic design.    With the large number of CASE tools are emerging out, you can also reach the design of the logic of a very high standard, you can usually a whole to better understand the needs of the database design aspects. 
  — Chardove 
  7. Understanding of your business in your system to determine 100 per cent from the customer point of view do not meet their needs before you in the ER (entity relationship) model by adding even a data table (how, you do not have models »skills that you see 9).    Know your business enterprises in the development stage after saving a lot of time.    Once you have defined the business needs, you can make their own decision-making by many. 
  — Rangel 
  Once you think you have defined the business, your best customers with a system of exchanges.    Customers using the terminology and explain to them that you think of and you have heard.    At the same time should also be used, and will have to wait vocabulary to express the relationship between the base system.    So you can allow your customer to correct your own understanding of the ER and then to design the next step. 
  — Teburlew 
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  8. Create a data dictionary and ER charts must take the time to create ER charts and data dictionary.    Which should at least include the type of data in each field in each table and the main foreign key.    ER charts, and create a data dictionary is a bit time-consuming but other developers to understand the whole design is totally necessary.    The sooner the creation of the future can help to avoid facing the possibility of confusion, which allows any understanding of the database of people have made it clear how access to data from the database. 
  — Bgumbert 
  One such as ER charts and other documents as the importance of how not be overemphasized, which showed that the relationship between the table very useful, and data dictionary shows how each of the fields and the use of any possible aliases.    The SQL expression of the document, it is absolutely necessary. 
  — Vanduin.chris.cj 
  9. Mode to create a chart is worth a thousand words: developers not only to read and realize it, but also use it to help themselves and user dialogue. 
  Model will help improve the effectiveness of collaboration, this early in the design of the database almost impossible to big problems.    Lane patterns do not have the very complicated, or even to be simple hand-written on a piece of paper on it.    Is to ensure that the logic of their relations in the future can produce benefits. 
  — Dana Daigle 
  10. Input and output from the start in the definition of database tables and field needs (input), should first check the existing design or have to reporting, query and view (output) to decide what to support these exports is necessary scale and Field.    Cite a simple example: If a customer needs to sort statements in accordance with the zip code, and Sub-sum, you must ensure that including a separate postcode field instead of a postcode into the address field, Rou. 
  — Peter.marshall 
  11. Statements skills to understand the user is usually how to report data: on-line or batch submitted statements »    Time interval is a daily, weekly, monthly, 
  Every quarter or every year »    If so could also consider a summary table.    System-generated in the statements of the main keys to management. 
  Users with system-generated table of the main keys in the retrieval of keys often will return to many of duplication of data.    This retrieval performance is relatively low and easily cause confusion. 
  — Kol 
  12. Understanding of customer needs it. This should be obvious, but the demand is from the customer (here from internal and external customers point of view). 
  Do not rely on users to write down the demand, the real needs of the customer in the head.    You want customers to explain their needs, and with the continued development, but also often asked customers to ensure their needs are still in the development of the purpose of.    The truth is the same one: "I only saw I know that I want is what" will inevitably lead to a lot of rework, because the database did not meet customers have never written down the demand for standards.    The worse you explain to them the needs of only your own, and may be completely wrong. 
  — Kgilson 

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