What potential issues can arise when deleting entries from a database using PHP?

When deleting entries from a database using PHP, potential issues can arise if proper validation and error handling are not implemented. For example, if a user tries to delete a non-existent entry or if there are dependencies on the entry being deleted, it can lead to errors or data inconsistencies in the database. To solve this, it is important to check if the entry exists before attempting to delete it and handle any errors that may occur during the deletion process. 

<?php
// Check if entry exists before deleting
$id = $_POST['id'];

// Connect to database
$conn = new mysqli($servername, $username, $password, $dbname);

// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

// Check if entry exists
$sql = "SELECT * FROM table WHERE id = $id";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    // Entry exists, proceed with deletion
    $sql = "DELETE FROM table WHERE id = $id";

    if ($conn->query($sql) === TRUE) {
        echo "Entry deleted successfully";
    } else {
        echo "Error deleting entry: " . $conn->error;
    }
} else {
    echo "Entry does not exist";
}

$conn->close();
?>

Keywords

SQL injection data integrity foreign key constraints transaction management error handling

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