Php 如何进行有效的sql查询？

下表如下：

表用户：

User_Id = 1,2,3;
User_Name: A,B,C;

表业务：

Business_Id = 1,2,3;
Business_Name: A,B,C;
Business_Detail: Details_A, Details_b, Details_c; 

表格访问：

Visit_Id = 1,2,3,4,5,6:
User_Id = 1,1,1,2,1,1;
Business_Id = 1,1,1,2,2,3;

我需要创建一个函数，返回访问列表和用户访问的业务信息。到目前为止，我已经得到了用户访问过的商店的列表，但不知道从那里去哪里

 function visit_count($user_id=1){
     global $database;
     $sql = "SELECT * FROM visits WHERE user_id ='{$user_id}' LIMIT 0 , 30";
     $result_set = $database->query($sql);
     $visits = mysql_fetch_array($result_set);

     //Get the unique ids of the business

    //Run another query that has the business information

    //combing both queries.

 }

谢谢你们的快速反应。这正是我所寻找的，我想我正在寻找的查询返回一个对象，如下所示：

Object:
  - Business:
     - Business_id;
     - Business_name;
     - Visit_counts;
  - Business:
     - Business_id;
     - Business_name;
     - Visit_counts;

因此，基本上，对象将具有业务信息和用户访问商店的次数

非常感谢您提供的所有帮助

您需要加入：

SELECT v.*, b.Business_Name, b.Business_Detail FROM visits as v 
JOIN Business as b on b.Business_Id = v.Business_Id
WHERE v.user_id ='{$user_id}' LIMIT 0 , 30

另外-使用mysqli并确保您是

编辑

---

按照@KHMKShore的建议使用预先准备好的语句。

首先，您应该了解，这是当前在PHP中使用sql的最佳实践

听起来你需要的是连接

$sql = "SELECT * FROM visits v
        JOIN business b ON b.Business_Id = v.Business_Id
        JOIN user u ON u.Business_Id = v.Business_Id
        WHERE v.user_id ='{$user_id}' LIMIT 0 , 30";

---

为每个用户尝试此SQL

尝试以下SQL代码：

SELECT business.business_id, business.business_name, COUNT(business.business_id) AS visit_counts
FROM business 
  LEFT JOIN visits
  ON business.business_id = visits.business_id
GROUP BY business_id, user_id

结果:

business_id |business_name |visit_counts
1            A              3
2            B              1
2            B              1
3            C              1

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既然这里已经有很多答案了，我想给大家一个我认为会对你们有很大帮助的答案。它纯粹是关于SQL的，从基础到中间。它充满了示例，包含了构建表等所需的所有代码，因此您可以自己实际运行和实验。帮你自己一个忙，读一读：）

business_id |business_name |visit_counts
1            A              3
2            B              1
2            B              1
3            C              1