oracle数据库常用的一些自定义函数

create or replace
FUNCTION "BINTOTEN" (strbin in varchar2) return NUMBER
IS

decvalue NUMBER(10);
binlen NUMBER(10);
indexa NUMBER(10);
currbit CHAR;
BEGIN

binlen := LENGTH(strbin);
decvalue := 0;
indexa := 0;
WHILE indexa < binlen LOOP
indexa := indexa + 1;
currbit := SUBSTR(strbin, indexa, 1);
IF (currbit != '0' AND currbit != '1') THEN
decvalue := -1;
ELSE
decvalue := decvalue * 2;
IF(currbit = '1') THEN
decvalue := decvalue + POWER(2, 0);
END IF;
END IF;
END LOOP;
RETURN decvalue;
END BINTOTEN;

create or replace
FUNCTION DATEDIFF (date1 IN DATE,date2 IN DATE) RETURN NUMBER
IS
datesx NUMBER(10);
secondsx NUMBER(20);
stra VARCHAR2(19);
strb VARCHAR2(19);
hh NUMBER(2);
mi NUMBER(2);
ss NUMBER(2);
BEGIN
stra := to_char(date1,'yyyy-mm-dd hh24:mi:ss'); -- 2010-12-12 00:00:00
strb := to_char(date2,'yyyy-mm-dd hh24:mi:ss');
hh := cast(substr(stra,12,2) as NUMBER) - cast(substr(strb,12,2) as NUMBER);
mi := cast(substr(stra,15,2) as NUMBER) - cast(substr(strb,15,2) as NUMBER);
ss := cast(substr(stra,18,2) as NUMBER) - cast(substr(strb,18,2) as NUMBER);
datesx := (to_date(substr(stra,1,10),'yyyy-mm-dd') - to_date(substr(strb,1,10),'yyyy-mm-dd'));
IF(datesx = 0) THEN
secondsx := hh*3600 + mi*60 + ss;
ELSE
secondsx := datesx*24*3600 + hh*3600 + mi*60 + ss;
END IF;
RETURN secondsx;
END DATEDIFF;

create or replace
FUNCTION "HXTOTEN" (str_a IN VARCHAR2) RETURN NUMBER
IS
str_b NUMBER(10);
str_c VARCHAR2(100);

BEGIN
str_c:=REPLACE(str_a,'0x','');
str_b:=0;
WHILE LENGTH(str_c) IS NOT NULL LOOP
str_b:=str_b*16+CASE SUBSTR(str_c,0,1)
when   'A'   then   10

when   'B'   then   11

when   'C'   then   12

when   'D'   then   13

when   'E'   then   14

when   'F'   then   15

ELSE     CAST(SUBSTR(str_c,0,1) AS INT)
END;
str_c:=SUBSTR(str_c,-(LENGTH(str_c)-1),LENGTH(str_c)-1);
END LOOP;
RETURN str_b;
END HXTOTEN;

create or replace
FUNCTION "ISNUMERIC" (str IN VARCHAR2)
RETURN NUMBER
IS
v_str FLOAT;
BEGIN
IF str IS NULL THEN
RETURN 0;
ELSE
BEGIN
SELECT TO_NUMBER (str) INTO v_str FROM DUAL;
EXCEPTION
WHEN INVALID_NUMBER THEN
RETURN 0;
END;
RETURN 1;
END IF;
END isnumeric;

create or replace
FUNCTION "MAX_TWO" (paramone IN NUMBER,paramtwo IN NUMBER) RETURN NUMBER

IS

max_param NUMBER(18,2);

BEGIN

IF paramone>=paramtwo THEN

max_param:=paramone;

ELSE

max_param:=paramtwo;

END IF;

RETURN max_param;

END MAX_TWO;

create or replace
FUNCTION "MIN_TWO" (paramone IN NUMBER,paramtwo IN NUMBER) RETURN NUMBER
IS
min_param NUMBER(18,2);

BEGIN

IF paramone>0 AND paramtwo>0 THEN

IF paramone>=paramtwo THEN

min_param:=paramtwo;

ELSE

min_param:=paramone;

END IF;

ELSE

min_param:=0;

END IF;

RETURN min_param;

END MIN_TWO;

create or replace
FUNCTION "TENTOBIN" (ix IN NUMBER) RETURN VARCHAR2
IS
vars VARCHAR2(1000);

xs NUMBER(10);
BEGIN

vars:='';

xs:=ix;
WHILE xs>0 LOOP
vars:=cast(MOD(xs,2) as VARCHAR2)||vars;--拼接字符串用“||”
xs:=FLOOR(xs/2);
END LOOP;

RETURN vars;

END TENTOBIN;

create or replace
FUNCTION "TENTOHX" (ix IN NUMBER) RETURN VARCHAR2
IS
rx VARCHAR2(10);
ixx NUMBER(10);
BEGIN
rx:='';
ixx:=ix;
WHILE MOD(ixx,16)>0 LOOP
rx:=
(CASE
WHEN MOD(ixx,16)<=9 THEN CAST(MOD(ixx,16) AS VARCHAR2)
WHEN MOD(ixx,16)=10 THEN 'A'
WHEN MOD(ixx,16)=11 THEN 'B'
WHEN MOD(ixx,16)=12 THEN 'C'
WHEN MOD(ixx,16)=13 THEN 'D'
WHEN MOD(ixx,16)=14 THEN 'E'
WHEN MOD(ixx,16)=15 THEN 'F'
END)||rx;
ixx:=FLOOR(ixx/16);
END LOOP;

IF ixx>0 THEN
rx:=
(CASE
WHEN MOD(ixx,16)<=9 THEN CAST(MOD(ixx,16) AS VARCHAR2)
WHEN MOD(ixx,16)=10 THEN 'A'
WHEN MOD(ixx,16)=11 THEN 'B'
WHEN MOD(ixx,16)=12 THEN 'C'
WHEN MOD(ixx,16)=13 THEN 'D'
WHEN MOD(ixx,16)=14 THEN 'E'
WHEN MOD(ixx,16)=15 THEN 'F'
END)||rx;
END IF;
RETURN rx;
END TENTOHX;