CREATE OR REPLACE FUNCTION IS_DATE(
IN_DATE IN VARCHAR2)
RETURN INTEGER
AS
FLAG INTEGER;
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 -1;
END IF;
END IF;
IF MON NOT IN ('01','02','03','04','05','06','07','08','09','10','11','12') THEN
RETURN -2;
END IF;
IF MON IN ('01','03','05','07','08','10','12') AND (TOD>'31' OR TOD<'01') THEN
RETURN -3;
END IF;
IF MON IN('04','06','09','11') AND (TOD>'30' OR TOD<'01') THEN
RETURN -4;
END IF;
IF MON='02' AND ((MOD(YER,4)=0 AND MOD(YER,100)<>0 OR MOD(YER,400)=0)) AND (TOD>'29' OR TOD<'01') THEN
RETURN -5;
END IF;
IF MON='02' AND ( TOD>'28' OR TOD<'01') THEN
RETURN -6;
END IF;
RETURN 0;
END IS_DATE;
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