def select *fields, &block
    obj = self.dup
    obj.instance_variable_set :@query_select, fields unless fields.empty?
    ret obj, &block
  end
def select *fields, &block
    obj = self.dup
    obj.instance_variable_set :@query_select, fields unless fields.empty?
    ret obj, &block
  end
Returns a new TableWrapper object which can be used to execute a select
 statement for the table selecting only the specified fields.
 If a block is given, executes the select statement and yields each row to the block.
 @param [*String/*Symbol] fields List of fields to select
 @return [JDBCHelper::TableWrapper]
 @since 0.4.0