Variable value assignment using RETURNING clause

Solution 1:

You need to use the INTO clause in the RETURNING to set the value being returned into your variable:

DECLARE myid OAMENI.id%TYPE;

INSERT INTO oameni 
VALUES 
  (default,'lol') 
RETURNING id INTO myid;

You also need to specify the data type of your variable; I'm glad to see postgresql supports %TYPE and %ROWTYPE.

Solution 2:

Adding to the main answer, it's worth noting that if you are doing this outside a stored procedure, you must wrap the code in a "DO" block, like so:

DO $$ 
DECLARE
    myid mytable.id%TYPE;
BEGIN
    INSERT INTO mytable (...) 
      VALUES (...)
      RETURNING id INTO myid;
END $$