gistfile1.txt

Welcome to psql 8.3.7, the PostgreSQL interactive terminal.

Type:  \copyright for distribution terms
       \h for help with SQL commands
       \? for help with psql commands
       \g or terminate with semicolon to execute query
       \q to quit

test_psql=> select null as data;
 data 
------
 
(1 row)

test_psql=> select null>10, null<10, null=null, 10=10 as data;
 ?column? | ?column? | ?column? | data 
----------+----------+----------+------
          |          |          | t
(1 row)

test_psql=>