how to force "select" method to retrieve just requested columns

MyTable.select() method results to the
SELECT my_table.* FROM my_table (or ALL column names are named explicitly)

Is there a way to retrieve just some rows, not all of them.

something what results to to the query like this:

SELECT my_table.columnA, my_table.columnB FROM my_table
(suppose there are also columns my_table.columnC, my_table.columnD ...
in the table).

Sometimes the tables I am working with are very wide (more than 100
columns) an I am connected them over the internet, so forcing the
select method to retrieve only requested rows will be great.

Best Regards

Petr

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