Subject using a stored procedure to return the value for an existing field in the table

Hi All,

I have a table, Parts, with 30 fields in it.

One is named: ExtraData5 and it's varchar(20).

the Parts table has millions and millions of rows and ExtraData5 is in each.

here's my question... when a normal statement:

select * from parts

where _some conditions_ 

is executed?  the literal table data for the column ExtraData5 is returned (along with all other columns)

What i want to do is override the data being returned from ExtraData5  and  i do not want to do it at the select statement.  i want a stored procedure to be called when data is being returned for ExtraData5.

i know i can write this:

select iif( (char_length(ExtraData5)<10), 'Less than 10', Extradata5) as ExtraData5 from Parts

but i have 1000s of places i'd have to change code.

is there a way i can write a StoredProcedure or trigger to have the "code" in the database return that value i want for the existing column and not just return the table data for that column?

sort of like a OnGetText() for the field BUT at the Firebird table level, not in the field in the query in my development environment.

FB 2.5

plus, i cannot do this:

select *,  iif( (char_length(ExtraData5)<10), 'Less than 10', Extradata5) as ExtraData5 from Parts

thank you in advance, i always learn a ton from this forum!!