【從本人QQ空間遷移】oracle驗證日期是否月底（未判斷日期是否正確）

  create or replace function CHECK_MONTHEND(IN_DATE VARCHAR2)
  RETURN INTEGER
AS
  YER VARCHAR2(4);
  MON VARCHAR2(2);
  TOD VARCHAR2(2);
BEGIN
  IF INSTR(IN_DATE, '-', 1, 1)=0 AND LENGTH(IN_DATE)=8 THEN
    YER :=SUBSTR(IN_DATE,1,4);
    MON :=SUBSTR(IN_DATE,5,2);
    TOD :=SUBSTR(IN_DATE,7,2);
  ELSE
    IF INSTR(IN_DATE, '-', 1, 1)=5 AND LENGTH(IN_DATE)=10 THEN
      YER :=SUBSTR(IN_DATE,1,4);
      MON :=SUBSTR(IN_DATE,6,2);
      TOD :=SUBSTR(IN_DATE,9,2);
    ELSE
      RETURN 0;
    END IF;
  END IF;
  IF MON NOT IN ('01','02','03','04','05','06','07','08','09','10','11','12') THEN
    RETURN 0;
  END IF;
  IF MON IN ('01','03','05','07','08','10','12') AND (TOD!='31') THEN
    RETURN 0;
  END IF;
  IF MON IN('04','06','09','11') AND (TOD!='30') THEN
    RETURN 0;
  END IF;
  IF MON='02' AND ((MOD(YER,4)=0 AND MOD(YER,100)<>0 OR MOD(YER,400)=0)) AND (TOD!='29') THEN
    RETURN 0;
  END IF;
  IF MON='02' AND ((MOD(YER,4)!=0 AND MOD(YER,100)<>0 and MOD(YER,400)!=0)) AND ( TOD!='28') THEN
    RETURN 0;
  END IF;
  RETURN 1;
 end CHECK_MONTHEND;
---------------------------------------------------------------------
統計類，上月月底
DB2中： 可根據當前日期求出上月月底日期    to_char(current date - day(current date) day,'yyyymmdd')