help with conversion functions

Hi,

I have written a function to update values in a table. The table structure
is as follows:
CREATE TABLE PointAttributes(AttributeId BIGINT NOT NULL,
PointId BIGINT NOT NULL,
StrValue VARCHAR(255),
NumValue FLOAT);

Based on the attribute datatype, i have to fill up either StrValue(if
datatype is character) or NumValue(if the datatype is numeric).

My function just updates the above table by providing values. The function
is as follows:

CREATE OR REPLACE FUNCTION PP_UpdatePointParameter(varchar,varchar,text);

the first 2 parameters specify the attributename and pointname. I am passing
the value as text in the 3rd parameter.
Now if the datatype is character, i have to set the StrValue field of the
table with text value else if the datatype of the attribute is numeric then
i have to convert the text to the suitable numeric type and assign it to the
NumValue.

I have problems in doing that.....i have used TO_NUMERIC(text) as specified
in the POSTGRESQL DOCUMENTATION. When i execute the function, it says
function to_numeric("unknown") does not exist. You may need to add explicit
type casts.

And also i am not sure what the return type of my function should. I have to
just update the table.
I need help on this.

> With Best Regards
> Pradeep Kumar P J
>
>