If I use a QSqlTableModel to access a MySQL database I can convert a TIMESTAMP field using the following:
QDateTime dateTime = index(section, column).data().
From MySQL 5.1 documentation:
A
DATETIMEorTIMESTAMPvalue can include a trailing fractional seconds part in up to microseconds (6 digits) precision. Although this fractional part is recognized, it is discarded from values stored intoDATETIMEorTIMESTAMPcolumns.
It seems like seconds is the best you can do with timestamp.