Sergey,

Thanks. I was wrong when I said the vfp would complain if I put in '' - empty string in the expression - {} or '' works. I don't need the dummy cursor. I must have had my parens wrong or something else wrong at the same time I was testing that - and got the 'the data sourc for this object must be a variable reference' message, and wrongly attributed it to having a string literal in the expression.






>Hi David,
>>I have not yet tried to create an index on my views with the datetime field as part of the index. What happens in an index expression such as index on clineitem + ttoc(dreserve), when dreserve is null?
>
>You can use NVL() function.

clineitem + ttoc(NVL(dreserve, {}))

>>Also, I was able to get it to work with this expression in the column control source:
>>
>>(iif(emptysqldate(v_sorsdt_all.dreserve),dummy.disempty,v_sorsdt_all.dreserve)))
>>
>>where dummy is a cursor with one row and an empty date)
>>and the column is readonly
>>
>>I have noticed that vfp always wants the control source to evaluate to a variable expression, if i put '' in place of dummy.disempty, it complains
>>
>>Also, I really don't understand the behaviour, but I think I need parens around the control source to get this to work, and, if I am not mistaken, I need to 'arrow down' on this, rather than hit enter, when in design - not sure on this???
>
>The following should work in the column's controlsource.

iif(emptysqldate(dreserve), {}, dreserve))