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This article will explain in detail how to understand the integrity constraint performance of database design. The content of the article is of high quality. Therefore, Xiaobian shares it with you for reference. I hope you have a certain understanding of relevant knowledge after reading this article.

Data integrity refers to the correctness, completeness and consistency of data, and is a criterion to measure the quality of database. Database integrity is ensured by various integrity constraints, so database integrity planning is database integrity constraint planning. What are the integrity constraints of database design?

Domain integrity: Columns in a database table must satisfy certain data types or constraints. Among them, constraints include the scope of values, precision and other provisions. Check is used to implement constraints. In database design tools, when defining the value range of a field, there is a Check button through which to define the value city of the field.

Referential integrity: It is to define the reference rules between the external code and the primary code. PK, FK, table-level triggers to achieve. The principle rule is that if an attribute (or group of attributes)f is the outer code of the elementary relation r, which corresponds to the principal code ks of the elementary relation s (elementary relations r and s are not necessarily different relations), then for each tuple in r the value on f must be either null (each attribute value of f is null) or equal to the principal code value of some tuple in s.

Entity integrity rule: If attribute a is the primary attribute of basic relation r, attribute a cannot be null. Because entity integrity rules are for basic relationships. A base table usually corresponds to a set of entities or many-to-many associations in the real world. Entities and relationships between entities in the real world are distinguishable, that is, they have some kind of identity, and database design relational models must comply with entity integrity rules.

User-defined integrity: User-defined integrity is a constraint condition for a specific relational database, reflecting the semantic requirements that the data involved in a specific application must meet. Relational models should provide mechanisms for defining and verifying such integrity so that they can be handled in a uniform, systematic way, rather than by applications. It is a set of business rules implemented with stored procedures and triggers.

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