sql - Trying to convert DBNull into a date without any luck so far. -

i loading value txtbox(driver) our sql database using filled txtbox(car registration) filter.

so able right driver vehicle. each vehicle can have number of people driving in time, using iif clause make sure current driver selected.

i getting error:

operator '>' not defined type 'dbnull' , type 'date'.

i know need convert dbnull date format, struggling so, have tried few things, , far have got to.

            dim cdriver new dictionary(of string, object)          cdriver.add("registration", txtreg.text)          dim currentdriver datatable          currentdriver = businessdata.verifierlogic.load("[car history]", cdriver)          dim currentdrivername string = ""         dim currentenddate datetime          each row datarow in currentdriver.rows             if datediff(dateinterval.day, row("end_date"), datetime.now) > 0                 currentdrivername = row("driver_name")                 currentenddate = row("end_date")                  iif(row("end_date") dbnull, "1 jan 1900", row("end_date"))             end if         next          txtdriver.text = currentdrivername     catch ex exception          msgbox(ex.message)      end try 

any appreciated

paul

so row("end_date") nullable? can use datarow-extension method field supports nullable types , typed:

for each row datarow in currentdriver.rows     dim enddate date? = row.field(of date?)("end_date")     if enddate.hasvalue andalso enddate.value > date.now        currentdrivername = row.field(of string)("driver_name")        currentenddate = enddate.value        exit ' otherwise overwriting these variables '     end if next