>>>>>What is a recommended method of comparing to NULL? I need to determine if a value of a field has changed. But when it changes to NULL value (and it is allow for this field) the comparison to NULL is NULL. Any suggestions on how to deal with this?
>>>>>
>>>>>Thank you.
>>>>
>>>>IF ISNULL(YourField)
>>>
>>>Yes, I know this function. What I was asking is how to compare current value with old value. This is the segment of code I was using:
>>>
>>>

>>>!(EVALUATE(FIELD(i)) == OLDVAL(FIELD(i), "V_MYTABLE"))
>>>

>>>
>>>What I ended up doing is checking if value before change was NULL and after change is NULL and use the result. As the following:
>>>
>>>

>>>IF (!ISNULL(EVALUATE(FIELD(i))) AND ISNULL(OLDVAL(FIELD
>>>(i), "V_V_MYTABLE"))) OR ;
>>>(ISNULL(EVALUATE(FIELD(i))) AND !ISNULL(OLDVAL(FIELD
>>>(i), "V_V_MYTABLE"))) OR ;
>>>!(EVALUATE(FIELD(i)) == OLDVAL(FIELD(i), "V_V_MYTABLE"))
>>>

>>>
>>>Thank you very much for your help.
>>
>>
>>I'm not really sure what it is you're trying to check here. Are you looking for a change in value? Or are you looking to see if the OLDVAL() is different than the current field value?
>
>I am looking if the current value is different from the old value.

Then wouldn't just a simple IF (VARTYPE(OLDVAL(FIELD(i))<>VARTYPE(EVALUATE(FIELD(i))) be sufficient, or do you need to know when character (or other type) value changes, too?