What potential issues can arise when using UNIQUE constraints in PHP and MySQL?

When using UNIQUE constraints in PHP and MySQL, potential issues can arise if the constraint is violated when trying to insert or update data. One common issue is handling the error that is thrown when a duplicate entry is attempted. To solve this, you can catch the exception and handle it accordingly in your PHP code. 

try {
    $pdo->query("INSERT INTO table_name (column_name) VALUES ('unique_value')");
} catch (PDOException $e) {
    if ($e->errorInfo[1] == 1062) {
        echo "Duplicate entry found!";
    } else {
        echo "Error: " . $e->getMessage();
    }
}

Keywords

UNIQUE constraints PHP MySQL data integrity duplicate entries

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