What are some best practices for avoiding duplicate/multiple database entries in PHP forms?

To avoid duplicate/multiple database entries in PHP forms, you can implement a check before inserting data into the database to see if a similar entry already exists. This can be done by querying the database with the input data to check for duplicates. Another approach is to use unique constraints in the database schema to prevent duplicate entries at the database level. 

// Check if the form data already exists in the database before inserting
$query = "SELECT * FROM table_name WHERE column_name = :input_data";
$stmt = $pdo->prepare($query);
$stmt->bindParam(':input_data', $input_data);
$stmt->execute();

if($stmt->rowCount() > 0) {
    // Entry already exists, show an error message or redirect back to the form
} else {
    // Proceed with inserting the data into the database
    $insert_query = "INSERT INTO table_name (column_name) VALUES (:input_data)";
    $insert_stmt = $pdo->prepare($insert_query);
    $insert_stmt->bindParam(':input_data', $input_data);
    $insert_stmt->execute();
}

Keywords

PHP forms database entries validation unique constraint

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