how to save null value in subsonic

Question

 Dim xbg As Rm

xbg.LobId = cmb_lob.SelectedValue
xbg.Mobile = mobno.Text
xbg.BusinessFax = faxno.Text
xbg.BusinessPhone = phno.Text
xbg.Save()

I have a combo box, which is not mandatory while input in the module. therefore user can select blank value in combo cox for which i want to save null in Oracle Database for that record. I had trid with following condition but fails to get result. you are requested to please help

if cmb_lob.selectedindex=-1 then 
    xbg.lob=dbnull 
else 
    xbg.LobId = cmb_lob.SelectedValue

Actual Problem arises when first user save record with selection in Combo box then user edit that record and select blank from Combo box. now i have to replace value of combox box with null at database.

Answer 1

try:

if cmb_lob.selectedindex <> -1 then 
    xbg.LobId = cmb_lob.SelectedValue
else
    xbg.LobId = Nothing 'suggested by John Shean (see comments)

So that if the value is selected only then assign it to field else leave it as it is (null)

Answer 2

Set it to null or whatever VB considers null - it will be set in the DB that way.

Answer 3

Try xbg.LobId = Nothing instead – By John Sheehan