Re: Converting char to varchar automatically - Mailing list pgsql-general

From Andrus
Subject Re: Converting char to varchar automatically
Date
Msg-id E6181F78CA7B4C21AAC815163AFE2789@dell2
Whole thread Raw
In response to Re: Converting char to varchar automatically  (Melvin Davidson <melvin6925@gmail.com>)
Responses Re: Converting char to varchar automatically
List pgsql-general
Hi!
 
>There really is no easy way to make a single ALTER for each table unless you use a programming language.
 
I’snt SQL a programming language ?
 
>However, adding a  GROUP BY c.relname,                  a.attname
>would certainly simplify editing. Then you can combine all the
>ALTER COLUMN's for each table.
I wrote
 
with stem as (
SELECT 'ALTER TABLE ' || quote_ident(n.nspname) || '.'
            || quote_ident(c.relname) as prefix ,
  string_agg(
      ' ALTER COLUMN ' || quote_ident(a.attname) || ' TYPE varchar(' || i.character_maximum_length ||')',
      ',' ) as body
  FROM pg_class c
    JOIN pg_namespace n ON n.oid = c.relnamespace
    JOIN pg_attribute a ON a.attrelid = c.oid
    JOIN pg_type t ON t.oid = a.atttypid
    JOIN information_schema.columns i ON (i.table_name = c.relname AND i.column_name = a.attname)
WHERE t.typname = 'bpchar'
   AND c.relkind = 'r'
   AND n.nspname <> 'pg_catalog' and not attisdropped
group by 1
)
 
select prefix || ' '|| body || ';' as statement
from stem
 
Is this prefect ?
 
Andrus.

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