How to loop through an array in php to search for database data

With the development of the Internet and its application, Web development has become one of the hottest fields at the moment. As one of the most commonly used scripting languages ​​in web development, PHP is undoubtedly the first choice for many front-end developers. As a server-side scripting language, PHP is widely used in web development. Among them, PHP performs particularly well in operating databases. This article will introduce a common method of using PHP loop array to search the database. I hope it will be helpful to PHP beginners.

1. What is a PHP loop array?

Before we start to introduce the method of PHP loop array to search the database, we need to first understand what a PHP loop array is. In PHP, looping through an array means performing the same operation on each element in the array. In practical applications, PHP loop arrays are often used to traverse data and operate on each element. For example, we can use PHP to loop over an array to output the values ​​of all elements.

2. Basic operation: extract data from the array

Before performing the PHP loop array search database operation, we first need to extract the desired data from the database. In PHP, we can use the "SELECT" statement to query data. The code below demonstrates how to query a database and extract data from it using PHP.

// 使用PHP连接数据库
$db = mysqli_connect("主机名", "用户名", "密码", "数据库名");

// 查询数据并将其存储在变量中
$sql = "SELECT * FROM data_table";
$result = mysqli_query($db, $sql);

// 将查询结果存储在数组中
$data_array = array();
while ($row = mysqli_fetch_assoc($result)) {
    $data_array[] = $row;
}

// 输出查询结果
print_r($data_array);

// 关闭数据库连接
mysqli_close($db);

In the above code, we use the mysqli_connect() function to connect to the database and use the SELECT statement to query data. The query results will be stored in the $result variable, and each row of results will be stored in the associative array $row using the mysqli_fetch_assoc() function. We use a loop to store each row of the associative array in an array called $data_array, and finally output the query results.

3. Loop array search database operation

After understanding the basic operations of extracting data from an array, we can start to loop array search database operation. In practical applications, it is often necessary to traverse the data in the database to find the data that meets the requirements and extract it. The following code demonstrates how to use a loop array to query the database.

// 使用PHP连接数据库
$db = mysqli_connect("主机名", "用户名", "密码", "数据库名");

// 查询数据并将其存储在变量中
$sql = "SELECT * FROM data_table";
$result = mysqli_query($db, $sql);

// 创建一个新数组
$new_data = array();

// 遍历每一个行
while ($row = mysqli_fetch_assoc($result)) {
    // 判断条件是否成立
    if ($row['column1'] > 20 && $row['column2'] == 'value') {
        // 将符合条件的行存储在新数组中
        $new_data[] = $row;
    }
}

// 输出查询结果
print_r($new_data);

// 关闭数据库连接
mysqli_close($db);

In the above code, we find matching data by traversing each row in the database. By using the IF statement, we can determine whether the columns in the row meet the specified conditions. For the rows that meet the conditions, we store them in a new array and finally output the query results.

4. Summary

In this article, we have learned about the basic concepts of PHP loop arrays, and introduced the methods of extracting data from arrays and using loop arrays to search the database. These skills are very important skills in web development. Whether it is data processing, website development, server construction, etc., you need to master these skills. I believe that through studying this article, readers can better master the application of PHP loop arrays and improve their skills.

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