ThinkPHP Database View model

Meaning: The View in this article refers to the database View model, rather than the View class in ThinkPHP to implement the ThinkPHP database View model.

Note: The View in this article refers to the database View model, rather than the View in ThinkPHP.
View class implementation.

A database View is a virtual table that extracts the required data columns from one or more basic tables as needed. In this way, you do not have to query Table B and Table c based on table.
Tables.

Views are not supported in some databases. ThinkPHP
Simulate and implement the database view, which can be used for multi-table joint query.

To use the View model in ThinkPHP, you only need to inherit the ViewModel and then set
ViewFields attribute. use the D method to instantiate the model.
View model instance

The existing user table and article table are as follows (the table prefix is
Test _):
User table (omitted ):
Article table (omitted ):
Create a View model file

2. Class ArticleViewModel extends ViewModel {
   
3. Public $ viewFields = array (
   
4. 'Article' => array ('aid ', 'title', 'content', 'uid '),
   
5. 'User' => array ('username', '_ on' => 'article. uid = user. uid '),
   
6. );
   
7. }
   
8. ?>

In this view model file, the model class inherits the ViewModel
View model and define $ viewFields attributes. each element includes a data table and the fields to be queried. In each table element
Element to define the association query conditions.

Save the file as Lib/Model/ArticleViewModel. class. php.
In the Action
Use View model in operation

In module operations, use the D method to instantiate the View model:

2. Class ArticleAction extends Action {
   
3. Public function index (){
   
4. Header ("Content-Type: text/html; charset = utf-8 ");
   
   
5. $ Dao = D ('articleview'); // instantiate the View
   
6. $ Article_list = $ Dao-> select ();
   
7. Print_r ($ article_list );
   
8. Echo'
   
   ';
   
9. // Print the executed SQL statement
   
10. Echo: '. $ Dao-> getLastSql ();
    
11. }
    
12. }
    
13. ?>
    

Access this method and print the result as follows:

1. Array
   
2. (
   
3. [0] => Array
   
4. (
   
5. [Aid] => 1
   
6. [Title] => Article 1
   
7. [Content] => Article 1 details ......
   
8. [Username] => admin
   
9. )
   
10. 
    
11. [1] => Array
    
12. (
    
13. [Aid] => 2
    
14. [Title] => Article 2
    
15. [Content] => Article 2 details ......
    
16. [Username] => Jack
    
17. )
    
18. 
    
19. )

The executed SQL statement is:

1. SELECT article. aid AS aid, article. title AS title, article. content AS content,
   
2. Article. uid AS uid, user. username AS username FROM test_article article JOIN test_user user ON
   
3. Article. uid = user. uid
   

From the above results, we can see that the view model simulates the implementation of the database view by using JOIN queries to aggregate data from multiple tables.