Check if an item's value is numeric or not

Question

Hello all,
does anybody know if there exists a funtion in PLSQL to check wether a string is numeric or not? How can this get implemented?
regards patrick

Answer 1

Thanks Peter, I was not asumming that null was a number...
A got a little modification to the code, that considers null as number (if you want so, if not... just replace "length(nvl(strTMP, 0))" with length(strTMP) ) and accept the decimals and negatives as numbers...
DECLARE
FUNCTION is_number(str IN VARCHAR2)
RETURN BOOLEAN IS
dummy NUMBER;
strTMP varchar(100);
BEGIN
strTMP := translate(str, '1-.,', '1');
--Validating only digits
for i in 1..length(nvl(strTMP, 0)) loop
dummy := TO_NUMBER(substr(strTMP,i,1));
end loop;
--Enforcing number meaning, here 1.2.3 and -126-3 will not pass
dummy := TO_NUMBER(str);
RETURN TRUE;
EXCEPTION
WHEN VALUE_ERROR
THEN
RETURN FALSE;
END is_number;
BEGIN
IF is_number('a') THEN
dbms_output.put_line('a is a number');
else
dbms_output.put_line('a is not a number');
END IF;
IF is_number('343E3') THEN
dbms_output.put_line('343E3 is a number');
else
dbms_output.put_line('343E3 is not a number');
END IF;
IF is_number(null) THEN
dbms_output.put_line('null is a number');
else
dbms_output.put_line('null is not a number');
END IF;
IF is_number(100) THEN
dbms_output.put_line('100 is a number');
else
dbms_output.put_line('100 is not a number');
END IF;
IF is_number('-1234') THEN
dbms_output.put_line('-1234 is a number');
else
dbms_output.put_line('-1234 is not a number');
END IF;
IF is_number('12.34') THEN
dbms_output.put_line('12.34 is a number');
else
dbms_output.put_line('12.34 is not a number');
END IF;
IF is_number('1.2.3.4') THEN
dbms_output.put_line('1.2.3.4 is a number');
else
dbms_output.put_line('1.2.3.4 is not a number');
END IF;
IF is_number('-12-3.4') THEN
dbms_output.put_line('-12-3.4 is a number');
else
dbms_output.put_line('-12-3.4 is not a number');
END IF;
END;
Just a little bit more work...
Regards,
Mike