
    $conn = mysqli_connect("host", "username", "password", "database", "port");
    mysqli_set_charset($conn, "utf8mb4");
      
    if ($conn->connect_error) {
        die "Not connected, error: " . $conn->connect_error;
    } else {
        echo "Connected.";
    }

   
    mysqli_close($conn);

https://www.php.net/manual/en/

Query


    mysqli_query($conn, $query);


    mysqli_execute_query()  - Prepares, binds parameters, and executes SQL statement
    mysqli_real_query()     - Execute an SQL query
    mysqli_multi_query()    - Performs one or more queries on the database
    mysqli_prepare()        - Prepares an SQL statement for execution
    mysqli_free_result()    - Frees the memory associated with a result

https://www.php.net/manual/en/mysqli.query.php