gistfile1.txt

begin;                                                                                              
                                                                                                    
  -- Could make this a temporary table, right?                                                      
  CREATE TABLE current_user_ids (id SERIAL PRIMARY KEY, user_id integer);                           
  create function current_user_id() returns integer language sql as $f$                             
    select user_id from current_user_ids where id = currval('current_user_ids_id_seq');             
  $f$;                                                                                              
                                                                                                    
  create table products(id integer primary key, price numeric);                                     
  insert into products values (1, 1.99), (2, 2.50);                                                 
                                                                                                    
  create function price(product_id integer, user_id integer) returns numeric language sql as $f$    
    select price + $2 from products where products.id = $1;                                         
  $f$;                                                                                              
                                                                                                    
  create view product_prices as (                                                                   
    select products.id, price, (select price(products.id, current_user_id())) as custom_price       
    from products);                                                                                 
                                                                                                    
  insert into current_user_ids (user_id) values (1);                                                
  select * from product_prices;                                                                     
                                                                                                    
  insert into current_user_ids (user_id) values (4);                                                
  select * from product_prices;                                                                     
                                                                                                    
/*                                                                                                  
                                                                                                    
INSERT 0 1                                                                                          
 id | price | custom_price                                                                          
----+-------+--------------                                                                         
  1 |  1.99 |         2.99                                                                          
  2 |  2.50 |         3.50                                                                          
(2 rows)                                                                                            
                                                                                                    
INSERT 0 1                                                                                          
 id | price | custom_price                                                                          
----+-------+--------------                                                                         
  1 |  1.99 |         5.99                                                                          
  2 |  2.50 |         6.50                                                                          
(2 rows)                                                                                            
*/