i need to calculate percentage grosssales with regionwise breakup on a particular segment ie Domestic Corp .  

My Query is 

```
 select    REGION_NAME,  
           round(ratio_to_report(nvl(sum(gross_sales_amt_t),0)) over ()*100) as Gr_Sales_domcorp 
 from      fact_mfdex_segment A 
 JOIN      dim_location B 
 ON        a.branch_code = b.branch_code 
 WHERE     to_date(DATE_SK,'YYYYMMDD') between '01-feb-2016' and '01-mar-2016' 
 AND       week_flag='Y' 
 AND       a.segments = 'Domestic Corp.' 
 group by  REGION_NAME;

```

I need to repeat the same query for HNI,RETAIL ETC. instead of Domestic Corp. rather than writing different query can i use my first query to add other segments. I have tried case statement but not working. Any help appreciated