oracle 滯納金的計算

create or replace function GET_ZNJ(
JFJZRQ in date,
YJE in number,
ZNJBL in number,
ZT in varchar2,
SJJFRQ in date,
MIAN_ZNJ in varchar2,
ZNJ_JMCS in number
) return NUMBER is
V_ZNJ NUMBER(14,2);
V_DATE date;
V_DAYS number;
begin
  V_ZNJ := 0;

  IF ZT <= '4' THEN
     V_DATE := SYSDATE;
  END IF;
  IF ZT >= '5' THEN
     V_DATE := SJJFRQ;
  END IF;

  V_DAYS := trunc(V_DATE) - trunc(JFJZRQ);
  IF MIAN_ZNJ = '1' THEN --不予減免1
  BEGIN
     V_ZNJ := CASE WHEN V_DAYS <= 0 THEN 0
                ELSE NVL(ROUND(V_DAYS * YJE * ZNJBL,2),0)
            END;
  END;
  ELSIF MIAN_ZNJ = '0' THEN --全部減免0
  BEGIN
     V_ZNJ := 0;
  END;
  ELSIF MIAN_ZNJ = '2' THEN  --日期減免2
  BEGIN
     V_ZNJ := CASE WHEN V_DAYS - ZNJ_JMCS <= 0 THEN 0
                ELSE NVL(ROUND((V_DAYS - ZNJ_JMCS) * YJE * ZNJBL,2),0)
            END;
  END;
  ELSIF MIAN_ZNJ = '3' THEN --比例減免3
  BEGIN
     V_ZNJ := CASE WHEN V_DAYS <= 0 THEN 0
                ELSE NVL(ROUND(ROUND(V_DAYS *  YJE * ZNJBL,2) * (1 - ZNJ_JMCS),2),0)
            END;
  END;
  ELSIF MIAN_ZNJ = '4' THEN --定額減免4
  BEGIN
     V_ZNJ := CASE WHEN V_DAYS <= 0 THEN 0
                ELSE NVL(ROUND(V_DAYS * YJE * ZNJBL,2),0) - ZNJ_JMCS
            END;
     IF V_ZNJ < 0 THEN
        V_ZNJ := 0;
     END IF;
  END;
  ELSE   --不予減免
  BEGIN
     V_ZNJ := CASE WHEN V_DAYS <= 0 THEN 0
                ELSE NVL(ROUND(V_DAYS * YJE * ZNJBL,2),0)
              END;
  END;
  END IF;
  -- 滯納金大于應繳金額時，滯納金=應繳金額
  IF V_ZNJ > YJE THEN
     V_ZNJ := YJE;
  END IF;
  return V_ZNJ;
end GET_ZNJ;