getting column names

["Armand Pirvu (home)" <armand.pirvu@xxxxxxxxx>]

Hi 

Can somebody please tell me if the below is possible ? 


I may not see the forest from the trees


Thanks
Armand




levregdb=# select * from foo1;
 audit_id | table_name 
----------+------------
     6012 | foo2
     6013 | foo2
     6014 | foo2

select * from foo2;

levregdb=# select * from foo2;
 foo2_add_by | foo2_add_date 
-------------+---------------
(0 rows)

levregdb=# \d foo2;
           Table "csiprev.foo2"
    Column     |     Type      | Modifiers 
---------------+---------------+-----------
 foo2_add_by   | character(10) | 
 foo2_add_date | character(10) | 



My intention is to have an output like

     6012 | foo2|foo2_add_by|foo2_add_date
     6013 | foo2|foo2_add_by|foo2_add_date
     6014 | foo2|foo2_add_by|foo2_add_date


select a.audit_id, a.table_name, b[1],b[2]
from 
foo1 a,
(select
array(
select 
column_name::text from 
information_schema.columns 
where 
table_name='foo2'
and 
(
column_name like '%add_by%'
or
column_name like '%add_date%'
)) b) as foo
;


 audit_id | table_name |      b      |       b       
----------+------------+-------------+---------------
     6012 | foo2       | foo2_add_by | foo2_add_date
     6013 | foo2       | foo2_add_by | foo2_add_date
     6014 | foo2       | foo2_add_by | foo2_add_date


But if I join back to foo1 like below I get 

select a.audit_id, a.table_name, b[1],b[2]
from 
foo1 a,
(select
array(
select 
column_name::text from 
information_schema.columns 
where 
table_name=a.table_name
and 
(
column_name like '%add_by%'
or
column_name like '%add_date%'
)) b) as foo
;

ERROR:  invalid reference to FROM-clause entry for table "a"
LINE 10: table_name=a.table_name
                    ^
HINT:  There is an entry for table "a", but it cannot be referenced from this part of the query.


Any idea what am I doing wrong ?
Can I do it ?


Thanks
Armand



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