I never tryed tio do it myself, but maybe it will help you:
» Symbian OS v6.1 Edition for C++ » API Reference » DBMS Rowsets » RDbRowSet
Accessing column values
Description
Small integral columns can be extracted as a wider integral type (up to 32-bits) provided that the following rule is used:
In order to extract column data for a row, either
the row must first have been retrieved using GetL(), or
the rowset object is updating or inserting the row
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Long columns can only be read using the RDbColReadStream object, and the above conditions also apply.
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signed columns must be extracted using a signed column accessor
unsigned columns must be extracted using an unsigned column accessor
Bit columns are considered to be single bit unsigned integers.