The difference between MySQL views and tables and their application scenarios

The difference between MySQL views and tables and application scenarios

The view (View) in MySQL is a virtual table, which is a visual table based on the SQL query result set , which can be queried, updated, or manipulated like a table. Views play an important role in database design. They can simplify complex data operations and improve data security and maintainability. In practical applications, views and tables have their own advantages and applicable scenarios.

1. The difference between MySQL views and tables

1. Definition method:
2. Table is the basic storage structure in the database, in the form of rows and columns Organize data.
3. View is a virtual table that is generated based on the query results of the original table and does not store actual data.
4. Storage data:
5. The actual data is stored in the table, and operations such as addition, deletion, modification, and query can be performed.
6. The view does not store actual data, only query definitions, and the view cannot be modified directly.
7. Data update:
8. You can add, delete, modify, and query data on the table.
9. When updating data on a view, it is actually an operation on the base table (that is, the table on which the view depends).
10. Data processing:
11. Tables can contain large amounts of data, are suitable for storing data, and support complex data operations.
12. Views can simplify data operations and provide specific views to facilitate users to query and manage data.

2. Application scenarios and code examples of MySQL views and tables

1. Application scenarios:
2. Data permission control: realizing user data through views Access permission control displays only the data that the user has permission to view.
3. Simplify complex queries: Creating views can encapsulate complex SQL query logic to facilitate users to query directly.
4. Data integration: Integrate data from multiple tables into one view to facilitate users to view data intuitively.

5. Example 1: Create a view
   Suppose there are two tables students and scores, as follows:

   CREATE TABLE students(
    id INT PRIMARY KEY,
    name VARCHAR(50),
    ageINT
   );
   
   CREATE TABLE scores(
    student_id INT,
    subject VARCHAR(50),
    score INT
   );

   Now we need to create a view to display the student's name, age and grade information:

   CREATE VIEW student_scores AS
   SELECT students.name, students.age, scores.subject, scores.score
   FROM students
   JOIN scores
   ON students.id = scores.student_id;

6. Example 2: Query view data
   We can query the data in the view through the following SQL statement:

   SELECT * FROM student_scores;

7. Example 3: Update view data
   Updating view data actually operates on the underlying table, for example:

   UPDATE student_scores
   SET score = 90
   WHERE name = 'Alice' AND subject = 'Math';

Summary:
MySQL views and tables each have their own role in the database. Tables are suitable for storing data, while views It is more suitable for simplifying complex data operations and improving data access efficiency. In actual applications, choosing to use tables or views based on specific needs can better optimize database design and data management.

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