PHP – Delete Data

Câu lệnh DELETE dùng để xóa record trong bảng.

DELETE FROM table_name
WHERE some_column = some_value

Chú ý WHERE trong cú pháp DELETE: Mệnh đề WHERE chỉ định record nào sẽ bị xóa. Nếu bạn bỏ qua mệnh đề WHERE, tất cả record sẽ bị xóa!

Ví dụ bảng MyGuests như sau

id firstname lastname email reg_date
1 John Doe john@example.com 2014-10-22 14:26:15
2 Mary Moe mary@example.com 2014-10-23 10:22:30
3 Julie Dooley julie@example.com 2014-10-26 10:48:23

Ví dụ sau xóa bản ghi với id = 3 trong bảng “MyGuests”:

MySQLi Object-oriented

<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";

// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
} 

// sql to delete a record
$sql = "DELETE FROM MyGuests WHERE id=3";

if ($conn->query($sql) === TRUE) {
    echo "Record deleted successfully";
} else {
    echo "Error deleting record: " . $conn->error;
}

$conn->close();
?>

MySQLi Procedural

<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";

// Create connection
$conn = mysqli_connect($servername, $username, $password, $dbname);
// Check connection
if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
}

// sql to delete a record
$sql = "DELETE FROM MyGuests WHERE id=3";

if (mysqli_query($conn, $sql)) {
    echo "Record deleted successfully";
} else {
    echo "Error deleting record: " . mysqli_error($conn);
}

mysqli_close($conn);
?>

PDO

<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDBPDO";

try {
    $conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
    // set the PDO error mode to exception
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    // sql to delete a record
    $sql = "DELETE FROM MyGuests WHERE id=3";

    // use exec() because no results are returned
    $conn->exec($sql);
    echo "Record deleted successfully";
    }
catch(PDOException $e)
    {
    echo $sql . "<br>" . $e->getMessage();
    }

$conn = null;
?>

Sau khi xóa record, bảng sẽ còn lại:

id firstname lastname email reg_date
1 John Doe john@example.com 2014-10-22 14:26:15
2 Mary Moe mary@example.com 2014-10-23 10:22:30