MySQL data integrity protection techniques

MySQL is currently the most commonly used open source relational database management system at the enterprise level. In data management systems, data integrity is crucial. Integrity refers to the accuracy and completeness of data, ensuring that there is no invalid or duplicate data and that the data is protected within the constraints within the database. This article will introduce MySQL's techniques to ensure data integrity.

1. Primary key constraints

The primary key is a column or a group of columns that uniquely identifies each record in the table. Primary keys can be defined in MySQL by using the PRIMARY KEY keyword. The primary key ensures the uniqueness of the data in the table and cannot be repeated at any time or null. When a table has a primary key defined, it automatically creates a unique index, which makes querying data faster.

2. Foreign key constraints

A foreign key is a field in one table that references the primary key of another table. Foreign keys can also be defined using the FOREIGN KEY keyword. The role of foreign keys is to ensure the consistency of data relationships, that is, if the foreign key of one table is linked to the primary key of another table, then when updating the record, you must ensure that if the primary key record is deleted, the foreign key record must also be deleted, or Set to NULL.

3. Non-null constraint

Non-null constraint means that certain columns in the table must be filled with values ​​and cannot be left blank. It can be defined using NOT NULL keyword. The role of the non-null constraint is to ensure that required fields in the table are not null. If the user leaves any required fields blank when inserting data, MySQL will report an error and notify the user to add the correct data.

4. Unique constraint

Unique constraint means that the value of a certain column must be unique. This can be defined using the UNIQUE keyword. The unique constraint ensures that a certain column of each row of data in the database table has a unique value. When a duplicate value is inserted, MySQL will report an error and notify the user to add the correct data.

5. Triggers

Triggers in MySQL are special stored procedures that can be automatically triggered at a specified location or time on the table. The role of triggers is to monitor and maintain data integrity. Users can use triggers to implement automatic checking of constraint scenarios and business rules.

6. Constraint Check

You can use CHECK constraints in MySQL to check data constraints. That is, the user can declare a constraint in the structure of the table that will be enforced when inserting or updating records in the table. CHECK constraint check is a mandatory check that can check any number of fields in the table to ensure that the data meets the requirements defined by the user.

7. Stored Procedure

A stored procedure is a block of program code that users can define and write to perform specific operations. Stored procedures in MySQL can implement complex business logic and data constraints to ensure data integrity. Similar to triggers, stored procedures can also add custom business rules and data checks to MySQL.

Summary:

The data constraint technology in MySQL is the key to ensuring data integrity. Database administrators must ensure that database tables are structured correctly and use appropriate constraint techniques to ensure data integrity. When developing an application, you need to consider whether the constraints are correctly defined and test them so that correctness issues can be refactored immediately if they occur. Initial efforts are critical in ensuring correctness in the database, because once the data is incorrect, it becomes more difficult to reconstruct the project.

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