Hi Everyone,
I was trying to collect table metadata with a description; the use case is that 
I need to show all columns of the tables whether it has the description or not. 
I tried the below query, but it only gives column details that have a 
description and ignore others if not. 

Postgres 11 | db<>fiddle


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Postgres 11 | db<>fiddle

Free online SQL environment for experimenting and sharing.
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create table test(id int);create table test1(id int Primary key );comment on 
column test.id is 'Test descr';

 SELECT c.table_schema,c.table_name,c.column_name,case     when c.domain_name 
is not null then c.domain_name    when c.data_type='character varying' THEN 
'character varying('||c.character_maximum_length||')'    when 
c.data_type='character' THEN 'character('||c.character_maximum_length||')'     
when c.data_type='numeric' THEN 
'numeric('||c.numeric_precision||','||c.numeric_scale||')'    else 
c.data_typeend as data_type,c.is_nullable, (select 'Y' from 
information_schema.table_constraints tcojoin 
information_schema.key_column_usage kcu      on kcu.constraint_name = 
tco.constraint_name     and kcu.constraint_schema = tco.constraint_schema     
and kcu.constraint_schema = c.table_schema and kcu.table_name = c.table_name 
and kcu.column_name = c.column_namewhere tco.constraint_type = 'PRIMARY KEY' ) 
as is_in_PK,(select distinct 'Y' from information_schema.table_constraints 
tcojoin information_schema.key_column_usage kcu      on kcu.constraint_name = 
tco.constraint_name     and kcu.constraint_schema = tco.constraint_schema     
and kcu.constraint_schema = c.table_schema and kcu.table_name = c.table_name 
and kcu.column_name = c.column_namewhere tco.constraint_type = 'FOREIGN KEY' ) 
as is_in_FK,pgd.description

FROM pg_catalog.pg_statio_all_tables as st  Left outer join 
pg_catalog.pg_description pgd on (pgd.objoid=st.relid)  left outer join 
information_schema.columns c on (pgd.objsubid=c.ordinal_position    and  
c.table_schema=st.schemaname and c.table_name=st.relname)where 
c.table_name='test'order by c.table_schema,c.table_name,c.ordinal_position; 

expected formate is :

| table_schema | table_name | column_name | data_type | is_nullable | is_in_pk 
| is_in_fk | description |



any suggestions?
Thanks,Rj

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