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How to use Mysql for multi-table joint query in ThinkPHP6

王林Original: 2023-06-20 08:55:042201browse

With the rapid development of the Internet, data storage and processing are becoming more and more important. For large websites, multi-table joint query is a very common operation. In this article, we will explore how to use Mysql in ThinkPHP6 to perform multi-table joint queries to obtain the data we need.

1. Create data tables

First, we need to create multiple tables and connect them. We can first create two tables: user and order. The user table contains the user's basic information (such as name, age, gender, etc.). The order table records the user's order information (such as order number, order time, order amount, etc.). These two tables can be linked by user ID. In the user table, we need to add a userID field as the primary key. In the order table, we need to add a userID field as a foreign key to associate with the userID field in the user table.

2. Writing the model

In ThinkPHP6, we can access the database by defining a model. We need to create a user model and an order model, corresponding to the above two tables respectively. In the user model, we need to define a method getUserJoinOrder() to jointly query the user table and order table and return the required data. The code is implemented as follows:

<?php
namespace appmodel;

use thinkacadeDb;
use thinkModel;

class UserModel extends Model
{
    protected $table = 'user';

    protected $pk = 'userID';

    public function getUserJoinOrder()
    {
        $result = Db::table('user')
                    ->alias('u')
                    ->join('order o', 'u.userID = o.userID', 'left')
                    ->select();
        return $result;
    }
}

In the above code, we use the table and alias methods under the think acadeDb namespace to specify the table name and alias. The join method is used to perform joint queries on multiple tables. It should be noted that in the join method, we need to specify the related fields of the two tables and the related method (left join, right join or inner join). Finally, we use the select method to execute the query and return the results.

3. Write the controller

In the controller, we can call methods in the model to access the database and pass the obtained data to the view layer. In this example, we create a UserController and write the getUserJoinOrder() method to call the getUserJoinOrder() method in the model. The code is implemented as follows:

<?php
namespace appcontroller;

use appmodelUserModel;
use thinkController;

class UserController extends Controller
{
    public function getUserJoinOrder()
    {
        $userModel = new UserModel();
        $users = $userModel->getUserJoinOrder();
        $this->assign('users', $users);
        return $this->fetch('user_list');
    }
}

In the above code, we use the assign and fetch methods under the thinkController namespace to pass data to the view layer and render the view.

4. Write the view

Finally, we need to create a view to display the data we obtained. In this example, we create a user_list.html file for display. The code is implemented as follows:

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <title>用户列表</title>
</head>
<body>
    <table border="1">
        <tr>
            <th>用户ID</th>
            <th>姓名</th>
            <th>年龄</th>
            <th>性别</th>
            <th>订单号</th>
            <th>订单时间</th>
            <th>订单金额</th>
        </tr>
        <?php foreach($users as $user): ?>
        <tr>
            <td><?php echo $user['userID']; ?></td>
            <td><?php echo $user['name']; ?></td>
            <td><?php echo $user['age']; ?></td>
            <td><?php echo $user['gender']; ?></td>
            <td><?php echo $user['orderID']; ?></td>
            <td><?php echo $user['order_time']; ?></td>
            <td><?php echo $user['order_price']; ?></td>
        </tr>
        <?php endforeach; ?>
    </table>
</body>
</html>

In the above code, we use PHP's foreach loop to traverse the obtained data and display it in an HTML table.

Summary

The above are the steps and code implementation for using Mysql to perform multi-table joint queries in ThinkPHP6. By building related tables, writing models, controllers, and views, we can get the data we need quickly and efficiently. At the same time, when writing models, we need to pay attention to the fields and related methods associated with multiple tables to ensure the accuracy of query results.

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