Mapping variables in Execute SQL Task

Hi Friends

I have a user variable  RowNumber (Integer) value=0 

Now I have 2 execute SQL Tasks and how to write & map a query like this:

1st Execute SQL Task:

select * from table where Row_Number = ?

And map parameter(?) to "Variable RowNumber  + 1"

2nd Execute SQL Task:

select * from table where Row_Number = ?

And map parameter(?) to "Variable RowNumber  + 2"

Royal Thomas