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Editor to share with you the analysis of data integrity in the SQL server database, I believe that most people do not know much about it, so share this article for your reference, I hope you can learn a lot after reading this article, let's go to know it!

The state in which all data values stored in the database are correct. If incorrect data values are stored in the database, the database is said to have lost data integrity. Detailed interpretation

The data in the database is input from the outside, and the input of the data will be invalid or error information due to a variety of reasons. To ensure that the input data conforms to the regulations has become the primary concern of the database system, especially the multi-user relational database system. As a result, data integrity is proposed. This chapter will describe the concept of data integrity and its implementation in SQL Server.

Data integrity (Data Integrity) refers to the accuracy (Accuracy) and reliability (Reliability) of data. It is proposed to prevent the existence of data that does not conform to the semantic provisions in the database and to prevent invalid operations or error messages caused by the input and output of error information. Data integrity can be divided into four categories: entity integrity (Entity Integrity), domain integrity (Domain Integrity), referential integrity (Referential Integrity), and user-defined integrity (User-definedIntegrity).

The database uses a variety of methods to ensure data integrity, including foreign keys, constraints, rules and triggers. The system well deals with the relationship between the four, and uses different methods according to different specific conditions, cross-use each other to make up for the shortcomings.

Data integrity: ensures the consistency and accuracy of data stored in the database.

Entity integrity constraints: constraints on a column (primary key (PRIMARY KEY) constraint)

Entity (row) integrity: requires all rows in the table to be unique, such as primary key values.

Domain integrity constraints: constraints on a row (default (default) constraint, check (check) constraint, non-null (not null) constraint).

Field (column) integrity: specifies a set of valid values for the column and determines whether null values are allowed. You can also enforce data integrity by defining the data type, format, and range of possible values in a column.

Referential integrity constraints: foreign key (foreign key) constraints related to primary keys

Referential integrity: ensure that the relationship between primary and external keywords is maintained.

User-defined constraints: in addition to implicit constraints, designers of relational databases can also set specific other constraints for the database, which are called "user-defined constraints".

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