drop  function if exists getProductPrices();
create or replace function getProductPrices( p_status product_status, p_sku varchar(100), p_title varchar(100) ) returns setof product as
'
declare
r product%rowtype;
begin
for r in SELECT * FROM product AS p WHERE p.id > 0 AND ( p.status= p_status OR p_status = '''' )AND ( p.title = p_title OR p_title = '' ) ORDER BY created_at loop
return next r;
end loop;
return;
end
'
language 'plpgsql';

select getProductPrices( 'D', 'wzp001', 'Product # 1' ) 

OR p_status = ''