HOW TO USE SAME SP ,WITH WHERE CLAUSE AND ALSO WITHOUT WHERE

Question

I HAVE TO DISPLAY CERTAIN COLUMNS IN GRID,WHEN I SELECT A 'SERIES' IN TEXTBOX.I HAVE THREE SERIES MAIN,SUB,ALL.MAINLY I WANT TO GET DISPLAY IN GRID'ALL' ONLY INCLUDING MAIN,SUB ALSO....I HAVE ONLY ONE SP WITH WHERE CONDITION FOR MAIN,SUB.....BECAUSE WHEN FORM LOAD..'ALL' WILL DISPLAY IN THAT TEXTBOX.NO NEED TO INSERT SERIES 'ALL',THEN CLICK BUTTON,GRID WILL DISPLAY.....WHAT CONDITION SHOULD APPL(IF...ELSE)Y?  WHERE IT ON .NET OR SP....?HOW TO WRITE CODING?