What are the essential steps for establishing a database connection, selecting a database, and executing a data select in PHP?

Establishing a database connection, selecting a database, and executing a data select in PHP involves several essential steps. First, you need to establish a connection to the database using the appropriate credentials. Then, select the database you want to work with. Finally, you can execute a data select query to retrieve the desired information from the database.

// Establishing a database connection
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "database_name";

$conn = new mysqli($servername, $username, $password, $dbname);

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

// Selecting a database
mysqli_select_db($conn, $dbname);

// Executing a data select query
$sql = "SELECT * FROM table_name";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    // Output data of each row
    while($row = $result->fetch_assoc()) {
        echo "id: " . $row["id"]. " - Name: " . $row["name"]. "<br>";
    }
} else {
    echo "0 results";
}

$conn->close();