Hi Muthuram,
Your comment is right but i have taken table type structure is different.
The logic which i have corrected based on your inputs.
var1 = SELECT T1.REGNAME, T1.SUBREGNAME, T2.PROD_ID, T2.SALES_AMOUNT
FROM MY_DEMO.REGION AS T1
INNER JOIN
MY_DEMO.SALES AS T2
ON T1.REGID = T2.REGID;
var2 = SELECT T1.REGNAME, T1.SUBREGNAME, T1.PROD_ID, T1.SALES_AMOUNT, T2.PRODNAME
FROM :var1 AS T1
INNER JOIN
MY_DEMO.PRODUCT AS T2
ON T1.PROD_ID = T2.PROD_ID;
OUTPUT_TABLE = SELECT SUM(SALES_AMOUNT) AS SALES_AMOUNT, SUM( SALES_AMOUNT - (SALES_AMOUNT * :DISCOUNT/ 100)) AS NET_AMOUNT,
PRODNAME, REGNAME, SUBREGNAME
FROM :var2
GROUP BY PRODNAME, REGNAME, SUBREGNAME;
END;