How to query all records in MySQL database using PHP

PHP is a very popular programming language that can be used to develop various types of web applications and websites. In the field of web development, the most common database management system is MySQL. In this article, we will explore how to query all records in a MySQL database using PHP.

Before we begin, we need to make sure that PHP and MySQL are installed. In addition, we also need a MySQL database and a table containing the data we want to query.

1. Establish a database connection

Before using PHP to query MySQL, we need to establish a database connection. We can use PHP's built-in mysql_connect() function to establish a connection.

<?php $db_host = &#39;localhost&#39;;    // 数据库服务器名称
$db_user = &#39;username&#39;;     // 数据库用户名
$db_password = &#39;password&#39;; // 数据库密码
$db_name = &#39;database_name&#39;; // 数据库名称

$conn = mysql_connect($db_host, $db_user, $db_password);

if (!$conn) {
    die(&#39;无法连接数据库: &#39; . mysql_error());
}

mysql_select_db($db_name, $conn);

echo &#39;数据库连接成功&#39;;

mysql_close($conn);
?>

2. Query all records

Once we have established a database connection, the next step is to query all records contained in the table. We can use the mysql_query() function to execute the query.

The following is a simple code example that uses the mysql_query() function to query all records in a table named "customer":

<?php $sql = "SELECT * FROM customer";

$result = mysql_query($sql);

if (!$result) {
    die(&#39;查询失败: &#39; . mysql_error());
}

while ($row = mysql_fetch_array($result)) {
    echo $row[&#39;id&#39;] . &#39; &#39; . $row[&#39;name&#39;] . &#39; &#39; . $row[&#39;email&#39;];
    echo "<br />";
}

mysql_free_result($result);
mysql_close($conn);
?>

In the above code, we use mysql_query( ) function executes the SELECT statement and queries all records. Then, we use the mysql_fetch_array() function to get each row of data in the result set and print it to the screen.

3. Summary

In this article, we discussed how to query all records from a MySQL database using PHP. First, we established a database connection and then queried all records in a table named "customer". Finally, we use the mysql_fetch_array() function to get all the data from the result set and display it on the web page.

It should be noted that the above code implementation may have security risks because we do not perform any verification on the input data. In practical applications, we need to ensure that the input data can be processed correctly while avoiding any security risks.

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