Returning the Duplicated ID - php

Question

Having this query
$query = 'INSERT INTO users(name) VALUES (:name)';
$stmt = $pdo->prepare($query);
$stmt->execute(['name' => $_POST['name']]);
INSERTing into The Table: Users where column name is UNIQUE.
Instead of doing two queries
$check = 'SELECT EXISTS (SELECT name FROM users WHERE name = :name);'
$stmt = $pdo->prepare($check);
$stmt->execute(['name' => $_POST['name']]);
if ($stmt->fetchColumn() == 0) {
$query = 'INSERT INTO users(name) VALUES (:name)';
$stmt = $pdo->prepare($query);
$stmt->execute(['name' => $_POST['name']]);
}
Is it possible using PDO to FETCH the Duplicated row id if $query failed to INSERT? Something like
$query = 'INSERT INTO users(name) VALUES (:name)';
$stmt = $pdo->prepare($query);
$stmt->execute(['name' => $_POST['name']]);
if ($stmt->duplicated() > 0) {
echo "Name already exists by the id number ".$stmt->duplicated()."";
}
In case it is impossible to return the Duplicated ID, Can I just tell if there is a Duplication without returning anything?
Example:
users
[id - name]
[1 - MARX]
[2 - MATH]
$query = 'INSERT INTO users(name) VALUES ('MARX')';
$stmt = $pdo->prepare($query);
$stmt->execute();
if ($stmt->duplicated() > 0) {
echo "Name already exists by the id number ".$stmt->duplicated()."";
} else {
echo "Name was Inserted";
}
Result: Name already exists by the id number 1

Answer 1

Create a unique index on users(name).
Then, catch the error when the unique index is violated.
This has nothing to do with on duplicate key update.
A unique index on name is highly, highly recommended for this purpose. Your code is not thread-safe. Two threads could have the same name. Each could check that it doesn't exist. And each could try to insert it. All that effort -- and you'll get duplicates anyway.
Let the database do what it is supposed to be doing -- protecting your data. Define the unique index/constraint.