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

When handling form submissions in PHP, it is important to check if the data being submitted already exists in the database to avoid creating duplicate entries. One way to do this is by querying the database before inserting the data to ensure there are no existing records with the same information. Additionally, using unique constraints or indexes on relevant columns can help prevent duplicate entries. 

// Check if the form has been submitted
if ($_SERVER["REQUEST_METHOD"] == "POST") {
  
  // Retrieve form data
  $name = $_POST["name"];
  $email = $_POST["email"];
  
  // Check if the data already exists in the database
  $query = "SELECT * FROM users WHERE name = '$name' AND email = '$email'";
  $result = mysqli_query($connection, $query);
  
  if (mysqli_num_rows($result) == 0) {
    // Insert the data into the database
    $insert_query = "INSERT INTO users (name, email) VALUES ('$name', '$email')";
    mysqli_query($connection, $insert_query);
    echo "Data inserted successfully!";
  } else {
    echo "Data already exists in the database!";
  }
}

Keywords

form submissions PHP database entries duplicate handling

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