What are the best practices for handling form submissions in PHP to avoid duplicate entries in a database?

When handling form submissions in PHP to avoid duplicate entries in a database, it is important to check if the data being submitted already exists in the database before inserting it. One way to achieve this is by using a unique constraint on the database table to prevent duplicate entries. Additionally, you can perform a query to check if the data already exists before inserting it. 

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

if($existingData->rowCount() == 0) {
    // Insert the data into the database
    $insertData = $pdo->prepare("INSERT INTO table_name (column_name) VALUES (:value)");
    $insertData->bindParam(':value', $submittedValue);
    $insertData->execute();
    echo "Data inserted successfully!";
} else {
    echo "Data already exists in the database!";
}

Keywords

PHP form submissions database duplicate entries validation

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