Problem: Joining each column of a "one row query" with the result of a "many row query"

Hello,

I have a query giving me the column_names with an unknown amount of rows.
This query is dynamically created by a pgsql function with the following
query inside:

select column_name from information_schema.columns where
table_schema='my_schema' and table_name='my_table' and "column_name" <>
'not_this_column1' and "column_name" <> 'not_this_column2' and "column_name"
<> 'not_this_column3'

Now I get some rows like:

column_name
------------
column_name1
column_name2
column_name3
.
.
.

There is an other query with one row result inside my pgsql function making
use of the result from the above query. The Part "column_name1,
column_name2, column_name3" the pgsql function can create on its own:

For example: select column_name1, column_name2, column_name3, ... from
my_schema.my_table where my_column1='abc' and my_column2=5

Now I get ONE row like this:

column_name1 | column_name2 | column_name3 | ...
-------------+--------------+--------------+----
value_clm1 | value_clm2 | value_clm3 | ...

In pgsql I do not get the column name in this query, right? That's sad,
because it would nearly solve my problem.

I need to find a way to get the result of the query in this way:

column_name | Value
-------------+-----------
column_name1 | value_clm1
column_name2 | value_clm2
column_name3 | value_clm3
.
.
.

In my opinion there are these ways?

1. combining both querys with a join, subselect or something like this?

2. Getting Postgres-SQL to write the column name into one row, how?

Can someone give me a hint to solve this problem? Or maybe someone has a
codesniplet?

Thank you for your help,

Christian