How can I prevent duplicate data from being saved in a CSV file when submitting a form in PHP?

To prevent duplicate data from being saved in a CSV file when submitting a form in PHP, you can first check if the data already exists in the CSV file before adding it. One way to do this is by reading the CSV file line by line and comparing the new data with existing data. If a match is found, you can prevent the data from being saved. 

// Check if the form has been submitted
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    // Get form data
    $newData = array($_POST['field1'], $_POST['field2'], $_POST['field3']);

    // Open the CSV file for reading
    $file = fopen('data.csv', 'r');
    
    // Check if the new data already exists in the CSV file
    $duplicate = false;
    while (($line = fgetcsv($file)) !== FALSE) {
        if ($line === $newData) {
            $duplicate = true;
            break;
        }
    }
    
    fclose($file);

    // If data is not a duplicate, append it to the CSV file
    if (!$duplicate) {
        $file = fopen('data.csv', 'a');
        fputcsv($file, $newData);
        fclose($file);
        echo "Data saved successfully!";
    } else {
        echo "Duplicate data found, not saved.";
    }
}

Keywords

PHP CSV file form submission duplicate data prevention

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