SQL

postgresql make each element in array distinct

SELECT ARRAY(SELECT DISTINCT unnest(t_column)) FROM t_name;

array aggre distinct postgres

SELECT ARRAY(SELECT DISTINCT e FROM unnest(ARRAY[a,b,c,d]) AS a(e))
FROM ( VALUES
  ('foo', 'bar', 'foo', 'baz' )
) AS t(a,b,c,d);