postgresql_functions.sql

CREATE OR REPLACE FUNCTION fn_days_in_month (DATE) RETURNS SMALLINT
  AS 'SELECT EXTRACT (DAYS FROM DATE_TRUNC (''month'', $1) + INTERVAL ''1 month - 1 day'')::SMALLINT;'
  LANGUAGE SQL IMMUTABLE RETURNS NULL ON NULL INPUT;

CREATE OR REPLACE FUNCTION fn_days_in_quarter (DATE) RETURNS SMALLINT
  AS 'SELECT ($1 - DATE_TRUNC (''quarter'', $1)::DATE + 1)::SMALLINT;'
  LANGUAGE SQL IMMUTABLE RETURNS NULL ON NULL INPUT;

CREATE OR REPLACE FUNCTION fn_days_in_year (DATE) RETURNS SMALLINT
  AS 'SELECT EXTRACT (DOY FROM DATE_TRUNC (''year'', $1) + INTERVAL ''1 year - 1 day'')::SMALLINT;'
  LANGUAGE SQL IMMUTABLE RETURNS NULL ON NULL INPUT;

CREATE FUNCTION fn_word_count (VARCHAR) RETURNS INTEGER
  AS 'SELECT COUNT (DISTINCT word)
        FROM (SELECT regexp_split_to_table ($1, ''\s+'') AS word)
          AS _;'
  LANGUAGE SQL IMMUTABLE RETURNS NULL ON NULL INPUT;