A bird's eye view of database system principles and database system principles

A bird's eye view of database system principles and database system principles

The database system is a data management system. First, we design the data. When talking about the data, we need to look at the development of the database system from the data management history. After reaching the database stage, we will begin to discuss our course.First, let's look at the Application Section:1. analyze the data to design and use the database. First, analyze the problem. The problems in the database world do not concern data! Therefore, analyze the data first. During data analysis, people often cannot solve the problem in one step. Therefore, the analysis of databases is generally from the macro to the micro, and abstract methods are used to Gradually refine the analysis of data. In the process of data abstraction, four models are created for different stages of data abstraction.
Since the four models are obtained through continuous refinement, these models naturally form a hierarchical relationship. These hierarchies solve different levels of problems, and are mapped to each other. This database structure should be designed after analysis.
2. To design a database, you must first make overall planning and then clarify the requirements. With a clear requirement, the following describes the specific design of each model.
In conceptual model design, a more important tool is the E-R diagram, through the E-R diagram can be more intuitive understanding of the system to be developed. If a good system is designed, you must first try its charm.
3. The most basic use of databases is the SQL language. The SQL language is actually the addition, deletion, modification, and query of tables. The expanded T-SQL of the SQL language is to add some process control. After you learn how to use the database language, you must learn how to manage the database.
4. The premise for managing and using a database system is that the system can ensure the correctness and security of data. To ensure this, you must manage the database system. The most direct reason for data correctness is to use constraints to limit the data range. Second, the transaction mechanism is used to ensure that data will not suffer unexpected losses as the system runs. Parallel Control of the system is required for parallel execution of multiple transactions in the system. In the last worst case, the original state will be restored.
Ensuring data correctness still does not meet people's needs, because data operations are permitted, just as we use access controllers in programming to limit data operations. We need to manage data security
To prevent system damage caused by illegal operations and unexpected faults.Let's look at the theoretical part.: Applications always need to have corresponding theories to support and guide. Here we start from the theory of table creation in order, and there is always a good or bad standard in table design, blind table creation creates many troublesome problems, which puts forward the paradigm. After a unified standard is set for creating a table, you can use a table to operate the table. There are many operations on the table. You can't tell why you can't do this. Therefore, we will study the theory of these operations for table operations.