>Hi. I have a form with a grid. The grid shows products. I want to add a column to show the average days in the warehouse. My warehouse data contains a date so I want the SQL to be:
>select cpartno, avg(date()-indate) as avgdays from whcuinvbin group by 1 having cpartno = THISFORM.THISGRID.COLUMN1.txtPart.Value
>

You could use a UDF as your controlsource, but be warned, this could be slow if you have a lot of data. Put (Thisform.CalcAvg(cPartNo)) in the controlsource for the textbox (you need to have the outer parentheses, and create a form method called CalcAvg as follows:

function CalcAvg
lparameter tcPartNo

if type('tcPartNo') <> 'C'
   messagebox('Invalid parameter')
   return
endif

select cpartno, avg(date()-indate) as avgdays ;
   from whcuinvbin ;
   where cPartno = tcPartNo

return AvgDays

Since you're only pulling records for the one part number, you don't need a group by clause.