string mysql_error ([ resource $link_identifier ] )

<?php
$server   = "localhost";
$database = "database";
$username = "user";
$password = "password";

$mysqlConnection = mysql_connect($server, $username, $password);
if (!$mysqlConnection)
{
  echo "Please try later.";
}
else
{
mysql_select_db($database, $mysqlConnection);
}
?>

<?php
$username = 'user';
$password = 'password';
$server = 'localhost';
// Opens a connection to a MySQL server
$connection = mysql_connect ($server, $username, $password) or die('try again in some minutes, please');
//if you want to suppress the error message, substitute the connection line for:
//$connection = @mysql_connect($server, $username, $password) or die('try again in some minutes, please');
?>

$servername='localhost';
$username='root';
$password='';
$databasename='MyDb';

$connection = mysqli_connect($servername,$username,$password);

if (!$connection) {
die("Connection failed: " . $conn->connect_error);
}

/*mysqli_query($connection, "DROP DATABASE if exists MyDb;");

if(!mysqli_query($connection, "CREATE DATABASE MyDb;")){
echo "Error creating database: " . $connection->error;
}

mysqli_query($connection, "use MyDb;");
mysqli_query($connection, "DROP TABLE if exists employee;");

$table="CREATE TABLE employee (
id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
firstname VARCHAR(30) NOT NULL,
lastname VARCHAR(30) NOT NULL,
email VARCHAR(50),
reg_date TIMESTAMP
)";
$value="INSERT INTO employee (firstname,lastname,email) VALUES ('john', 'steve', 'johnsteve@yahoo.com')";
if(!mysqli_query($connection, $table)){echo "Error creating table: " . $connection->error;}
if(!mysqli_query($connection, $value)){echo "Error inserting values: " . $connection->error;}*/