How To Check That Is 'select All' Checkbox Of The Parameter Is Selected

My parameter pass the id of the parameter to my query while its name is displyed on the parameter combo.

I have a report on which there is a text field.

1,On this field i want's to display the name of the parameter.

If select all check box is check i want's to show Report of AllFieldName.

other wise it should be comma separate like Report of aa,cc.

e.g

I have field myfield with fieldname aa,bb,cc dd value with fieldid as 1,2,3,4

I am passing this parameter in the query like

select ... where id in( @fieldid)



2,I am exporting this report in a excel format.

How can i pass the parameter in the query string ,submit it.

{How to check select all parameter or particular parameter e.t.c }