How to make “case-insensitive” query in Postgresql?

Is there any way to write case-insensitive queries in PostgreSQL, E.g. I want that following 3 queries return same result.

SELECT id FROM groups where name="administrator"

SELECT id FROM groups where name="ADMINISTRATOR"

SELECT id FROM groups where name="Administrator"

Use LOWER function to convert the strings to lower case before comparing.

Try this:

SELECT id 
  FROM groups
 WHERE LOWER(name)=LOWER('Administrator')