(1) Concept
A database is a collection of information. Each collection contains one or more records in a unified form, and the records are composed of fields. The collection is usually called a table, and the records are called is the row in the table.
Databases are generally divided into: flat file database (TEXT), hierarchical database, network database, relational database (mysql),objectand objectrelational database!
(2) Relational database is the liberation of programmers to develop software
Since the flatware file database must be directly contacted with the operating system, when the application needs to edit this information , you must ensure that the fields and have the correct form. This form of interface is expensive, because it requires a 3rd generation language (3GL) and requires highly skilled personnel for a long time to develop! For example, programmers must consider the data Logical and physical representation, for example, to read anintegerfrom a file, the programmer needs to know whether it is written in text form or binary form. When data flows between files and applications, certain conventions must be followed. Therefore, the efficiency of flat file database programs generally depends on the hard work and level of programmers! Compared with MYSQL, data independence is achieved, and structure independence is also achieved! Therefore, programmers do not need to bear the burden of data management! Put aside Many internal details of database processing! This is the most important reason for the emergence of RDBMS! It is also the reason for its popularity!
(3) Excellent program - object-relational database model
In the database model , MYSQL is a relational database, but the relational model is not a patent of MYSQL. The innovation of database theory is continuing. Some basic principles of advanced technology can also be used in the relational model. If you are a programmer proficient in 3GL, use flat files. The database can not only develop excellent programs! It also has great advantages in basic data processing, programming control, and resource utilization! If you need to frequently read and write a large amount of data, you can use the positioning pointer to read the specified data. , Fixed lengthIndex, The so-called load problem is easily solved, and the control is very flexible and convenient.Securityissues, hierarchical and network model concurrency models can be used! Of course, the most What is important is the sensitivity of the programmer, and a well-designed index table is very important!
The advantage of MYSQL mainly lies in its physical storage: the MYLSAM table supports 3 row modes and fixed-length row ideas for data processing Flexible processing, and the use of file descriptors to read and write tables, system memory buffering andcachingare all reasons for MYSQL's fast data processing capabilities! At the same time, you can use the convenience brought by physical storage to process data Repair, defrag and more!
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