Hi , I have a field that user enter data like;

"POZITIVE",
"5.34",
"+++",
"3.43",
"7.00",
"NEGATIVE",

This field mainly stores numeric values, but users also enter data as
characters as needed.

Now I need to get the average of valid values. Obviously, I can't use AVG()
on these.
I have done this. I get all the data to the client, and calculate the
average by iterating the rows.
Of course I know it's not the best way.

Is it possible to do this with stored procedures?
Is there any keywords that validate the numeric values in stored procedures?

Thank you.