Delete php using mysel

I need to delete some data in my web project, and I am using PHP language and MySQL database. This article will introduce how I used PHP and MySQL to complete the data deletion operation.

1. Create MySQL database and tables
Create a table in the MySQL database (the example table is named "todos") to store our data entries. The table should contain at least the table's id, title, creation date, update date and description columns. You can also add additional columns to better organize your data.

2. Connect to the MySQL database
Create a PHP file and name it "delete.php". In this file, connect to the MySQL database using PHP. You will also need to use PHP functions to retrieve data from the MySQL table. You can use the following PHP code:

<?php
// 连接数据库
$con = mysqli_connect("localhost","my_user","my_password","my_db");
// 检查连接是否成功
if (mysqli_connect_errno()){
  echo "连接 MySQL 失败: " . mysqli_connect_error();
  exit();
}
//从表格中检索数据
$result = mysqli_query($con,"SELECT * FROM todos");
while($row = mysqli_fetch_array($result)){
  echo $row['id'] . " " . $row['title'];
  echo "<br>";
}
// 关闭连接
mysqli_close($con);
?>

3. Create a form using HTML
Add an HTML form in the "delete.php" file to receive the ID of the data item the user wants to delete. You will need to use the method POST to send the form data into a PHP script with delete functionality.

<form action="delete_item.php" method="post">
  ID: <input type="text" name="id"><br>
  <input type="submit" value="删除">
</form>

4. Create PHP code to delete data from the table
Create a new PHP file and name it "delete_item.php". In this file, use PHP to connect to the MySQL database and delete the data item using the ID provided by the user. Below is the complete "delete_item.php" file, which includes code on how to delete data from a MySQL table using PHP:

<?php
// 连接数据库
$con = mysqli_connect("localhost","my_user","my_password","my_db");
// 检查连接是否成功
if (mysqli_connect_errno()){
  echo "连接 MySQL 失败: " . mysqli_connect_error();
  exit();
}
// 从表格中删除数据
$id = $_POST['id'];
$sql = "DELETE FROM todos WHERE id=".$id;
if ($con->query($sql) === TRUE) {
  echo "数据删除成功";
} else {
  echo "Error deleting record: " . $con->error;
}
// 关闭连接
mysqli_close($con);
?>

The above PHP script matches the ID entered by the user with the ID in the MySQL table, and delete matching data items. If the deletion is successful, the message "Data deletion successful" will be displayed. If there are errors, an appropriate error message is displayed.

Finally, you need to implement appropriate security measures in your web application to ensure that only authorized users can delete data. For example, you can require users to log in to access deletion functionality, or limit deletion permissions to application administrators only.

Conclusion
Deleting data from web applications can be easily done using PHP and MySQL. When writing deletion code, be sure to take appropriate security measures to avoid data loss or access by unauthorized third parties.

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