code: @Nullable
  	public static String firstString(PreparedStatement stmt) throws SQLException {
  		ResultSet rs = stmt.executeQuery();
  		String s = rs.next() ? rs.getString(1) : null;
  		stmt.close();
  		return s;
  	}
docs: Execute the query, get the String value in the first row and column of the result set, and
  close the statement.
  
  @param stmt
  must already have parameters set
  @return null if the result set is empty
  @since 3.0.0