Object Oriented Style

  $stmt = $maindb->prepare("UPDATE some_table SET
        MyStringColumn = ?,
        MyIntColumn = ?
      WHERE MyColumn = ?
    ");
  $stmt->bind_param("sii", $MyStringColumn, $MyIntColumn, $MyRowId);
  $stmt->execute();
  $stmt->close();

How many rows were affected

  $stmt->execute();
  $NumOfAffectedRows = $stmt->affected_rows;
  $stmt->close();

Procedural Style

	$result = mysqli_query($dblink, "UPDATE some_table SET
						image_filename = '',
						something_else = 4
					WHERE indexer = $destid
					");
	if ( ($result != TRUE) || (mysqli_affected_rows($dblink) < 1) )
		die("ERROR - Couldn't update");

Maths Operations In Update Queries

	mysqli_query($dblink, "UPDATE some_table SET some_value_a = some_value_a + 1, some_value_b = some_value_b + 10  WHERE id = 1");

Add text to an existing text field

  UPDATE MyTable SET MyFieldName = CONCAT_WS('', MyFieldName, ' [UserBlocked ]') WHERE user_id = %d"

  UPDATE MyTable SET MyFieldName = CONCAT_WS('', MyFieldName, ' [UserBlocked ', Now(), ' Reason: %d]') WHERE user_id = %d"

  //N.B. CONCAT_WS allows this to work if the field is currently null (CONCAT will fail) and the first '', is required
  //as it is what CONCAT_WS inserts between each of the following string fields (nothing in this case)