Say it is numeric field and you want to use 0 for 'all'...

({?Param}=0 or {table.field} in minimum{?Param} to maximum{?Param})

 

Often people end up using a UNION command to insert an '...All' record for dynamic string params

You are using 2 params (Start and End) and they are numeric, correct?

Both field require that some value be entered. You have to tell your end users what to enter that is equivalent to 'All'. The value has to be of the same data type the param is (like zero for numeric). Then in the select expert you use an OR statement.

The first part of the OR just states the value you want to be 'All' = the param. This way when they user puts that value in it evaluates to TRUE and ignores the rest of the statement which means the select statement will not filter any data (or returns all rows).

The second part of your statement is what you want to it to do if the user does NOT enter the identified 'All' value (zero), like return values between two params. YOu end up with somehting like

 

{?ItemStart}=0 or {item.item} in {?ItemStart} to {?ItemEnd}

 

If the end user needs to be able to evaluate between 0 and an actual number then they would need to enter 0 in both start and end

 

({?ItemStart}=0 and {?ItemEnd}=0) or {item.item} in {?ItemStart} to {?ItemEnd}