How to write database forms in PHP

With the increasing development of Internet technology, the use of Web applications is becoming more and more widespread. The development of a good Web application is inseparable from the support of a database. Database forms are an essential part of Web applications and are the key to data interaction and data management.

As one of the most popular web development languages, PHP has the advantage of being widely used. Writing database forms in PHP makes it very convenient to manipulate the database and interact and manage data in web applications. This article will introduce how to write database forms in PHP.

1. Connect to the database

In PHP, to operate the database, you first need to establish a connection with the database. A common method is to use MySQLi or PDO extension library. This article uses the MySQLi extension library as an example.

//Connect to the database
$mysqli = new mysqli("localhost", "username", "password", "database");
if($mysqli ->connect_errno) {

die("连接失败:" . $mysqli->connect_error);

}
?>

In the above code, localhost represents the server address where the database is located, username represents the username to connect to the database, and password represents the database connection The password, database represents the database name. The connect_errno attribute indicates the connection error code, and the connect_error attribute indicates the connection error information. When the connection fails, use the die function to output error information and terminate the execution of the program.

2. Create a form

After successfully connecting to the database, you need to create a form. Forms can be constructed using HTML, for example:

<input type="text" name="name" placeholder="姓名">
<input type="email" name="email" placeholder="电子邮件">
<input type="submit" value="提交">

The above code means creating a form containing name and email and submitting it to the insert.php page for processing.

3. Insert data

In the form processing page insert.php, you need to obtain the data in the form and insert it into the database. Using PHP's prepared statements can effectively prevent SQL injection attacks. For example:

//Connect to the database
$mysqli = new mysqli("localhost", "username", "password", "database");
if( $mysqli->connect_errno) {

die("连接失败:" . $mysqli->connect_error);

}

//Get form data
$name = $_POST['name'];
$email = $_POST[ 'email'];

//Preprocessing statement
$stmt = $mysqli->prepare("INSERT INTO user(name, email) VALUES (?, ?)");
$stmt->bind_param("ss", $name, $email);
$stmt->execute();

//Output the insertion result
if($stmt->affected_rows > 0) {

echo "插入成功";

} else {

echo "插入失败";

}

/ /Close the connection
$stmt->close();
$mysqli->close();
?>

In the above code, the prepare method is used to prepare a band SQL statements with placeholders can effectively prevent SQL injection attacks. Use the bind_param method to bind the data in the form to the placeholder, and execute the execute method to insert the data into the database. At the same time, the insertion results are output.

4. Query data

Querying data is also done using the MySQLi extension library. The method is as follows:

//Connect to the database
$mysqli = new mysqli("localhost", "username", "password", "database");
if($mysqli->connect_errno) {

die("连接失败:" . $mysqli->connect_error);

}

// Query data
$sql = "SELECT name, email FROM user";
$result = $mysqli->query($sql );

//Output query results
if($result->num_rows > 0) {

while($row = $result->fetch_assoc()) {
    echo "姓名：" . $row['name'] . "，邮箱：" . $row['email'] . "<br />";
}

} else {

echo "没有数据";

}

//Close the connection
$result->close();
$mysqli->close();
?>

In the above code, use the query method Query the database, use the fetch_assoc method to obtain data from the result set, use a while loop to traverse the result set, and output the query results.

In short, writing database forms in PHP is an almost indispensable skill in the Web development process. This article introduces the knowledge of connecting to the database, creating forms, inserting data, querying data, etc. Programmers need to deeply understand this knowledge and continue to practice and optimize it in order to achieve greater success in the field of web development.

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