ms access - Calculating average days (with DateDiff and NULL) -

ms access - Calculating average days (with DateDiff and NULL) -

ms access (jet-sql)

i want find mean difference between 2 dates, in days. 1 date contains null values want exclude calculation. please note can't utilize where function because have other aggregate calculations in select statement (not shown here) don't want filter.

my lastly attempt:

select avg(iif(datedischarge not null, datediff('d',datevalue(daterandomisation),(datevalue(datedischarge))),null)) dtdis_dtrand table grouping variable

thanks help,

rob

to exclude calculation need exclude rows avg() 0 has affect.

exclude them select:

... table datedischarge not null

ms-access null average datediff