Database management system, database

Database management system, database

Today, I summarized database and drew two diagrams. The following describes the learning knowledge based on my diagram.

Figure 1

Figure 2

1. The database lifecycle is divided into three major stages: planning, design, and implementation. The three stages are progressive links. Then, we will give a detailed description in three aspects.

First, the planning stage mainly describes what the software is doing. A Conceptual Model is generated based on user needs. The most vivid method is to use the ER model, that is, the entity contact model.

Next, let's talk about the design stage. This stage is mainly divided into logical design and physical design. Of course, it also involves the development environment. Here we will introduce two types: power builder and SQL sever2000, in fact, we have used SQL sever2008, and this book is obviously "too old ". Logical design generates a logical model. In Figure 2, it should appear after the DBMS software is selected, mainly dependent on the software. It has three types: hierarchy, mesh, and relational model (two-dimensional table ). Currently, the most widely used relational model is the relational model, which contains multiple relational models, the purpose of logical design is to convert the conceptual model designed at the conceptual design stage into a logical structure that matches the data model supported by the DBMS on the selected machine, here we will convert the ER model to the relational mode. You can use the SQL language to define the relational mode. Physical Design generates a physical structure, that is, the storage record format, storage record arrangement, and access method of the database. Unlike logical design, physical design relies entirely on hardware.

Finally, the database is implemented. After the database is designed, you should start to use it. At this time, you should compile and debug the corresponding applications. Then, a small amount of data will be stored into the database and the database trial run will begin. Debugging of performance and functions. Of course, maintenance is essential. We should consider data security.

The role of Figure 2 is DBS (Database System), which includes DBA (Database Administrator), DBMS (software), and DB (database ). The application uses DBMS to access the data in the database, and then the DB processes the query results and reports them to the application. DBMS contains DDL compilation programs (three levels and two layers of database definition), DML compilation programs or interpretation programs (add, delete, modify, and query ), there is also a data dictionary-DD that stores the three-level structure definition. When DBS are running, DBMS needs to monitor them. The minimum logical unit for DBS to run is "transaction". database operations must be performed or withdrawn in the unit of transactions. DBAs use some programs and DD systems in DBMS to master the work of DBS. Therefore, the DBA's responsibilities are quite important and should be attended by highly qualified persons.

This is my understanding of this book. For more information, please advise!

What management software is the database management system?

A database management system is a database institution. It is a system software responsible for data organization, data manipulation, data maintenance, control, protection, and data services in databases.


What management software is the database management system?

A database management system is a database institution. It is a system software responsible for data organization, data manipulation, data maintenance, control, protection, and data services in databases.