>What is a good sql method of getting member months at a hmo.?
>I use vfp5.0 ;have member tables with effective and expiration dates.
>Is medicaid so there are some members who go in and out maybe as much
>as 3 times a year.
>
>Calculating the RPM's of a revolving door in St. Louis........

I assume your table has these fields: person_id, effdate, expdate and also that there may be more than one of each person_id (maybe three per year of data) in this table.

SELECT person_id, SUM(monthdiff(effdate,expdate)) AS months ;
 FROM yourtable INTO CURSOR whatever WHERE NOT EMPTY(effdate) ;
 AND NOT EMPTY(expdate) GROUP BY person_id

FUNCTION monthdiff
PARAMETERS dStartDate, dStopDate
LOCAL nStartYear, nStopYear, nStartMonth, nStopMonth
nStartYear = YEAR(dStartDate)
nStopYear = YEAR(dStopDate)
nStartMonth = MONTH(dStartDate)
nStopMonth = MONTH(dStopDate)
nMonths = (12*(nStopYear-nStartYear))+(nStopMonth-nStartMonth)
RETURN nMonths

If you wish to round off months differently, you can tweak the monthdiff function, using other native VFP date functions.