There are a few special sql commands that I used often recently,mark them here.

1: Show all the columns' name

SELECT * FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME='yourtablename';

another solution

\d 'yourtablename'

SELECT               
  pg_attribute.attname,format_type(pg_attribute.atttypid,pg_attribute.atttypmod) 
FROM pg_index,pg_class,pg_attribute 
WHERE 
  pg_class.oid = 'nygeotwitters'::regclass AND
  indrelid = pg_class.oid AND
  pg_attribute.attrelid = pg_class.oid AND 
  pg_attribute.attnum = any(pg_index.indkey)
  AND indisprimary;