Converting an Integer to Enum in PostgreSQL

Question

I have created a custom data type enum like so:

create type "bnfunctionstype" as enum ( 'normal', 'library', 'import', 'thunk', 'adjustor_thunk' );

From an external data source I get integers in the range [0,4]. I'd like to convert these integers to their corresponding enum values. How can I do this? I'm using PostgreSQL 8.4.

Answer 1

SELECT (ENUM_RANGE(NULL::bnfunctionstype))[s]
FROM   generate_series(1, 5) s

Answer 2

create function bnfunctionstype_from_number(int)
    returns bnfunctionstype
    immutable strict language sql as
$$
    select case ?
        when 0 then 'normal'
        when 1 then 'library'
        when 2 then 'import'
        when 3 then 'thunk'
        when 4 then 'adjustor_thunk'
        else null
    end
$$;