Re: Why not used standart SQL commands?

Den 2022-01-08 kl. 19:25, skrev Ali Koca:
> Hello,
>
> I'm seeing \dt used for "show tables", \l used for "show databases". Why
> not standart SQL syntax words? Why specified PostgreSQL commands?
> I can't figure out that.
>
> Ali
>
>

The psql backslash commands is just helper commands that wraps the 
actual sql. With the -E, --echo-hidden option when starting psql you can 
see the real sql.


The \dt command for instance uses this query:

SELECT n.nspname as "Schema",
   c.relname as "Name",
   CASE c.relkind WHEN 'r' THEN 'table' WHEN 'v' THEN 'view' WHEN 'm' 
THEN 'materialized view' WHEN 'i' THEN 'index' WHEN 'S' THEN 'sequence' 
WHEN 's' THEN 'special' WHEN 't' THEN 'TOAST table' WHEN 'f' THEN 
'foreign table' WHEN 'p' THEN 'partitioned table' WHEN 'I' THEN 
'partitioned index' END as "Type",
   pg_catalog.pg_get_userbyid(c.relowner) as "Owner"
FROM pg_catalog.pg_class c
      LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace
      LEFT JOIN pg_catalog.pg_am am ON am.oid = c.relam
WHERE c.relkind IN ('r','p','')
       AND n.nspname <> 'pg_catalog'
       AND n.nspname !~ '^pg_toast'
       AND n.nspname <> 'information_schema'
   AND pg_catalog.pg_table_is_visible(c.oid)
ORDER BY 1,2;


/Nicklas Avén