oracle自定义函数的执行时间

if (len = 15) then
-- 检查是否全为数字，否则转换操作会抛异常，导致程序崩溃，ascii('0') = 48, ascii('9') = '57'
--for i in 1 .. 15 loop
WHILE i <= 15 LOOP
--ch := substr(id, i, 1); -- 非数字会报错
c := ascii(substr(id, i, 1));
if c < 48 or c > 57 then
exit;
end if;
i := i + 1;
end loop; IF i = 16 THEN
trans := TRUE;
ret := '19' || substr(id, 7, 2);
END IF;
end if;

if (len = 18) then
-- 2006-10-18 luocm
-- 检查是否全为数字，否则转换操作会抛异常，导致程序崩溃，ascii('0') = 48, ascii('9') = '57'
--for i in 1 .. 17 loop
WHILE i <= 17 LOOP
--ch := substr(id, i, 1); -- 非数字会报错
c := ascii(substr(id, i, 1));
if c < 48 or c > 57 then
exit;
end if;
i := i + 1;
end loop;

c := ascii(substr(id, 18, 1));
--if i <> 18 OR (c <> 88 AND c <> 120) OR c < 48 or c > 57 THEN -- 第18位为[0-9xX]
if i = 18 AND (c = 88 OR c = 120 OR c >= 48 or c <= 57) THEN -- 第18位为[0-9xX]
trans := TRUE;
ret := substr(id, 7, 4);
end if;
end if;

IF trans = FALSE THEN
i := 1;

WHILE i <= 8 LOOP
c := ascii(substr(birthday, i, 1));
if c < 48 or c > 57 then
exit;
end if;
i := i + 1;
end loop;

IF i > 8 THEN
yyyy := substr(ltrim(rtrim(birthday)), 1, 4);
IF yyyy < 1900 OR yyyy > 2000 THEN
ret := '';
ELSE
ret := yyyy;
END IF;
ELSE
ret := yyyy;
END IF;
END IF;

RETURN ret;
end f_extract_birthday;