Inserting form data into MYSQL, checking to see if the name already exists

joe69

This should be an easy one for you all.
Scenerio:
I have a form. when submitted it enters the info into the database.

I need to check to see if said first name and last name already exist in the DB and if they do it jsut doesnt insert it again.. Having trouble with getting started here
Any help would be appreciated. If you need some code tell me what you need and I'll post it.

Thanks

Joe

devinemke

run a SELECT query first to see if any records match your criteria, then conditionally run the INSERT query if the SELECT query yields no results.

laserlight

The best way is to declare (first_name, last_name) as UNIQUE. Then, an attempt to insert a first name and last name pair that already exists in the table will result in a unique constraint violation which you can check and report back to the user.

However, if your database management system does not enforce unique constraints, then you would have to select from the table and see if any results are returned. If there are no results, then you assume that the first name and last name pair is unique, and thus you insert it. The catch is that there is a possible race condition where two users attempt to insert the same first name and last name pair at about the same time (but then this is very unlikely).

joe69

devinemke. Thats what I am having trouble with. the syntax of that select query and how to check to see if any records match.

joe69

to laser light. Thank you for the input. I looked at my DB management system and I can set each to unique but not as a pair. so if I had more than one person with the same firstname. it wouldnt insert them or lastname

laserlight

the syntax of that select query and how to check to see if any records match.

It depends on your database extension, but generally it would be along the lines of:

SELECT COUNT(*) FROM users WHERE first_name='$first_name' AND last_name='$last_name' LIMIT 1

For example, using the PDO extension:

$stmt = $db->prepare("SELECT COUNT(*) FROM users WHERE first_name=:first_name AND last_name=:last_name LIMIT 1");
$stmt->bindParam(':first_name', $first_name, PDO::PARAM_STR);
$stmt->bindParam(':last_name', $last_name, PDO::PARAM_STR);
$stmt->execute();
if ($stmt->fetchColumn() == 0) {
    // No existing entry, so insert user entry.
} else {
    // There is an existing entry, so inform user to try again.
}