Software engineering (SE) is a discipline that studies the use of engineering methods to build and maintain effective, practical and high-quality software. It involves programming languages, databases, software development tools, system platforms, standards, design patterns, etc.
The goal of software engineering is to develop software products with modifiability, effectiveness, reliability, comprehensibility, maintainability, reusability, adaptability, portability, traceability and interoperability that meet the needs of users on the premise of given cost and schedule. Pursuing these goals can help improve the quality and efficiency of software products and reduce maintenance difficulties.
Software engineering principles refer to the principles that must be followed in software development around engineering design, engineering support, and engineering management. There are four basic principles of software engineering:
1) select appropriate development models
This principle is related to system design. In system design, software requirements, hardware requirements and other factors are mutually restrictive and influencing each other, often requiring tradeoffs. Therefore, the variability of requirements definition must be recognized and controlled by appropriate development paradigms to ensure that software products meet user requirements.
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2) adopt appropriate design methods
In software design, modularization, abstraction and information concealment, localization, consistency and adaptability are usually considered. Appropriate design methods help to achieve these characteristics in order to achieve the goals of software engineering.

3) provide high quality engineering support
He who wants to do his work well must use his tools well. In software engineering, software tools and environments are important to support software processes. The quality and cost of a software engineering project depends directly on the quality and utility of the support provided to the software project. 4) pay attention to the management of the development process
The steps required to produce a software product that ultimately meets the requirements and meets the engineering goals. Software engineering process mainly includes development process, operation process and maintenance process.
They cover activities such as requirements, design, implementation, validation, and maintenance. Requirements activities include problem analysis and requirements analysis. Problem analysis captures requirements definition, also known as software requirements specification. Requirements analysis generates functional specifications. Design activities generally include general design and detailed design. The outline design establishes the entire software system structure, including the subsystem, the module and the related level descr iption, each module interface definition. Detailed design of module specifications available to programmers, including data structure descr iptions and processing descr iptions in each module. Implementation activities translate design results into executable program code. The validation activities run through the entire development process, and the verification after completion ensures that the final product meets the user's requirements. Maintenance activities include extension, modification and refinement during use. The above process is accompanied by management process, support process, training process, etc.

database system

First, what is a database? As the name implies, it is the warehouse where the data is stored. Strictly speaking, it is a collection of data that is stored in a computer for a long time and can be organized and Shared. Second, why do we use databases? Throughout the three stages of data management, including the stage of manual management, file system and database system, the database system has obvious advantages: simplicity, speed, labor saving, convenience, centralized control of data (sharing, reduction of redundancy, consistency, things support, integrity, security, etc.). Again, how do we use the database? We are required to use it under the unified management and control of the database management system, and we need to understand the respective rights of end users, programmers, advanced users and database administrators. The database management system mentioned above refers to a layer of data management software located between users and the operating system, which realizes the unified management, control and maintenance of databases and data objects. Its functions also include data definition function, data organization storage and management, data manipulation function, database thing management and operation management, database establishment and maintenance function. And, with database, application system, database manager composition database system.
A model is a simulation and abstraction of the features of an object in the real world. Data model is also a kind of model. It is an abstraction of data characteristics in the real world. In other words, it is used to describe data, organize data and perform data
The operation. It is the core and foundation of database system. Data models here can be divided into two categories: the first type, the conceptual model, also known as the information model, which is used to model data and information according to the user's point of view, mainly for database design. Second, the logical model and the physical model. Among them, logical models include hierarchical model, network model, relational model, object-oriented model, object relational model, etc. It models data from the viewpoint of a computer system and is mainly used for DBMS implementation. The physical model is an abstraction of the lowest layer of data, which describes how the data is represented and accessed within the system. The data model consists of three parts: data structure, data operation and integrity constraint.