How to use PHP to query data based on age

With the widespread application of PHP in web development, PHP developers are facing more and more problems. One of the common problems is how to query data based on age. This article will introduce how to use PHP to query data based on age.

Before implementing this function, we need to first understand some basic syntax and functions of PHP. PHP is a scripting language that can be used with HTML embedding and can be used to write web applications. One of PHP's biggest advantages is its powerful string processing capabilities, and it can also implement process control, array operations, etc. through built-in functions.

Suppose now we have a set of data, such as employee information, including name, age, department and other information. We need to query data based on the age of employees. First, we need to get the age value entered by the user from the front desk and the employee information in the database. Then, we can use a foreach loop to traverse all employee information in the database, compare the ages, find qualified employees, and output their information.

The following is a PHP code that implements this function:

<?php //这里要与数据库连接，可以使用mysqli或PDO等连接方式
$conn = mysqli_connect("localhost","root","password","database");

if (!$conn)
{
    die(&#39;连接失败: &#39; . mysqli_connect_error());
}
//从前台获取用户输入的年龄值
$age= $_GET["age"];

//用foreach循环遍历数据库中的所有员工信息
$sql="SELECT * FROM employee";
$result= mysqli_query($conn,$sql);
foreach($result as $row){   

    //将年龄进行比较，找出符合条件的员工，并将其信息输出
    if($row[&#39;age&#39;] == $age){    
        echo "员工编号：".$row[&#39;id&#39;]."<br/>";
        echo "姓名：".$row['name']."<br>";
        echo "年龄：".$row['age']."<br>";
        echo "部门：".$row['department']."<br>";
    }
}

mysqli_close($conn); //关闭数据库连接
?>

Through the above code, we can query and output all qualified employee information in the database based on age. In actual development, some optimizations and improvements need to be made according to specific situations, such as adding paging functions, using AJAX to obtain data asynchronously, etc.

When implementing this function, you need to pay attention to several points:

1. Database connection: You must connect to the database before implementing the query function;
2. Data acquisition: required Obtain the age value entered by the user from the front desk and obtain employee information from the database;
3. Data processing: You need to use a foreach loop to traverse all employee information, compare it, find the data that meets the conditions, and then add its related information output.
4. Database closure: The database connection needs to be closed after the search is completed.

In short, PHP, as a powerful scripting language, can well solve some practical problems in network development. You only need to practice more in practice to become an excellent PHP developer. .

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