In the current database realm, more and more people are starting to take access. It is a powerful database management system and MIS development tools, with user-friendly interface, easy to learn and easy to use, simple development, flexible interface and so on. I am now using access to experience some of the experience here to communicate with you.
Techniques for Database design
1. Unified planning
The so-called database design refers to the whole process from the analysis of the current non Computer Management database system to the final realization of the database system managed by the computer. It includes the design of tables, queries, reports, etc. The general principles should be considered in terms of improving the efficiency of data processing and facilitating data processing.
Taking the design of student achievement management system as an example, in the design of the table, is the whole school students to design a table, or grade set table, after analysis by grade set table will improve data processing speed and ease of processing, the corresponding need to set a parameter table to describe the various grades of some cases, This allows the parameters to be extracted from the parameter table later in the process of data processing. Taking into account the possibility of error in the input of students ' grades, it is necessary to design the corresponding secondary score table, so that each score two input, and then set up the corresponding master and Vice query to check whether the results of the main vice table is consistent, inconsistent to modify. For example, to carry out a very paragraph, a single section, the total score per segment of the data statistics, you can design the corresponding table with Visual Basic procedures for processing and statistical data automatically filled in the corresponding table. To minimize the number of fields in the design of a field, for example, the student rank has the class rank and the grade rank, we may take these two places to use a field to express, if uses "m/n" to indicate, "The M" indicates the class rank, "The N" indicates the grade rank, this also may use the Visual Basic procedure to realize. In the design of the report is based on the table to establish a report or query based on the report, it is clear that the query based on the establishment of the report is flexible and convenient, you can easily modify the query and the relevant conditions in the query to print out the required reports. In a word, in order to design a reasonable database object, we should consider the database design comprehensively.
2. Set up key words and relationships between tables
The setting of keywords in the design of a table is important, and setting keywords can increase the speed of operations such as queries. Sometimes you can use multiple fields as keywords. The relationship between the two tables is also important, for example, if there is no correct relationship between the master and the secondary scores, then the principal-Vice query will not get the correct result.
3. Design a default value for a field
The default value of a field can sometimes be noted. For example, in a numeric field, because some records may not have entered data, there may be some incorrect results when processed with the Visual Basic program (whether this is a bug in Access 97), but when the default value is set to 0, everything works.
