Re: column information from view

On 9/14/18 2:35 PM, Sebastian P. Luque wrote:
> Hello,
> 
> I'm trying to generate a table with information on columns from a
> temporary view that simply selects a subset of columns from a persistent
> view in a given schema.  The persistent view joins a number of tables
> with columns that may or may not have a description entered.  I need a
> table with a list of columns from the temporary view, and the matching
> descriptions from the underlying persistent view.
> 
> Here's my attempt at listing the temporary view's columns and respective
> descriptions:
> 
> SELECT cols.ordinal_position, cols.column_name,
>    col_description(cl.oid, cols.ordinal_position::INT)
> FROM pg_class cl, information_schema.columns cols
> WHERE cols.table_catalog='dbname' AND cols.table_schema='some_schema' AND
>    cols.table_name = 'persistent_view' AND cols.table_name = cl.relname
> ORDER BY cols.ordinal_position::INT;
> 
> The problem, of course, is that it lists columns from the persistent
> view, instead of the subset of them in the temporary view.  Is there a
> better way to do that?  Hopefully this makes sense.

create temp view c_data as select source_id, geography_desc from 
catfish_data ;

\d c_data
                        View "pg_temp_3.c_data"
      Column     |       Type        | Collation | Nullable | Default
----------------+-------------------+-----------+----------+---------
  source_id      | integer           |           |          |
  geography_desc | character varying |



SELECT cols.ordinal_position, cols.column_name, 
 

   col_description(cl.oid, cols.ordinal_position::INT) 
 

FROM pg_class cl, information_schema.columns cols 
 

WHERE cols.table_catalog='aquaculture' AND cols.table_schema ilike 
'pg_temp%' AND 

   cols.table_name = 'c_data' AND cols.table_name = cl.relname 
 

ORDER BY cols.ordinal_position::INT; 
 


  ordinal_position |  column_name   | col_description 
 

------------------+----------------+----------------- 
 

                 1 | source_id      | NULL 
 

                 2 | geography_desc | NULL

> 
> Thanks,
> --
> Seb
> 
> 


-- 
Adrian Klaver
adrian.klaver@aklaver.com