Can I create another view? subtract from total_deposit - total_loan_amount
CREATE VIEW v_total_deposit (total_deposit) as
CREATE VIEW v_total_loan (total_loan) as
@moonir01 MINUS is a set operator, not arithmetic one. You have to subtract two numbers:
CREATE VIEW balance AS SELECT NVL((SELECT TOTAL_DEPOSIT FROM V_TOTAL_DEPOSIT),0) - NVL((SELECT TOTAL_LOAN FROM V_TOTAL_LOAN),0) AS balance FROM DUAL
but you really don't need these views.