Fetching rows from a cursor PostgreSQL

Question

I have the cursor code:

BEGIN;
DECLARE cliente_cursor 
CURSOR FOR SELECT * FROM cliente;

I want to read all the content from the Table 'cliente':

With the use of a cursor. I have the code working for SQL Server:

DECLARE cliente_cursor CURSOR
      FOR SELECT * FROM cliente
OPEN cliente_cursor
FETCH NEXT FROM cliente_cursor;
While @@FETCH_STATUS=0
BEGIN
     FETCH NEXT FROM cliente_cursor;
End
CLOSE cliente_cursor
DEALLOCATE cliente_cursor

And I want to have a working code for PostgreSQL.

I have been looking for a solution & seen people usually suggest using functions. I wonder if there is any way in this PostgreSQL DBMS to create something similar to the code in SQL Server.

I had written this code:

CREATE OR REPLACE FUNCTION MyFunction()
RETURNS setof cliente AS $$
DECLARE 
cursor_cliente CURSOR FOR SELECT * FROM cliente;
rec cliente%ROWTYPE;
 BEGIN
 OPEN cursor_cliente;
loop
--fetch the table row inside the loop
FETCH cursor_cliente INTO rec;
-- check if there is no record
   --exit from loop when record not found
   if not found then
        exit ;
   end if;
end loop;
RETURN;
END;
$$ LANGUAGE plpgsql;

But when I run it, I only get:

select MyFunction();

Any idea what should the code be instead?

Any help would be appreciated a lot!

Answer 1

CREATE OR REPLACE FUNCTION foo() RETURNS setof cliente 
   language plpgsql AS $$
DECLARE
  x cliente%rowtype ;
BEGIN 
  FOR x IN SELECT * FROM cliente loop
    RETURN NEXT x;
  END loop;
END $$;

SELECT * FROM foo();

it can also be done with an explicit cursor.

CREATE OR REPLACE FUNCTION foo() RETURNS setof cliente
  language plpgsql as $$
DECLARE 
  x cliente%rowtype ;
  cliente_cursor CURSOR FOR SELECT * FROM cliente; 
BEGIN
  FOR x IN cliente_cursor loop
    RETURN NEXT x;
  END loop;
END $$;

SELECT * FROM foo();

The function is going to persist so either give it a useful name and keep it around or drop it after you are done.

If you want a private name for the function pg_temp.foo will be private to your session.