How to fix 2F005: function_executed_no_return_statement in PostgreSQL

-- Problematic: ELSE branch missing RETURN
CREATE FUNCTION get_status(code integer)
RETURNS text AS $$
BEGIN
  IF code = 1 THEN
    RETURN 'Active';
  ELSIF code = 2 THEN
    RETURN 'Inactive';
  -- Missing ELSE RETURN!
  END IF;
END;
$$ LANGUAGE plpgsql;

-- Fixed: All branches return
CREATE FUNCTION get_status(code integer)
RETURNS text AS $$
BEGIN
  IF code = 1 THEN
    RETURN 'Active';
  ELSIF code = 2 THEN
    RETURN 'Inactive';
  ELSE
    RETURN 'Unknown'; -- Added RETURN in ELSE
  END IF;
END;
$$ LANGUAGE plpgsql;

-- Problematic: Exception caught but no return
CREATE FUNCTION safe_divide(a numeric, b numeric)
RETURNS numeric AS $$
BEGIN
  RETURN a / b;
EXCEPTION
  WHEN division_by_zero THEN
    RAISE NOTICE 'Division by zero attempted';
    -- Missing RETURN here!
END;
$$ LANGUAGE plpgsql;

-- Fixed: Return a default value after exception
CREATE FUNCTION safe_divide(a numeric, b numeric)
RETURNS numeric AS $$
BEGIN
  RETURN a / b;
EXCEPTION
  WHEN division_by_zero THEN
    RAISE NOTICE 'Division by zero attempted';
    RETURN 0; -- Added RETURN
END;
$$ LANGUAGE plpgsql;

-- Alternative: Re-raise the exception
CREATE FUNCTION safe_divide(a numeric, b numeric)
RETURNS numeric AS $$
BEGIN
  RETURN a / b;
EXCEPTION
  WHEN division_by_zero THEN
    RAISE EXCEPTION 'Cannot divide by zero';
END;
$$ LANGUAGE plpgsql;

-- Problematic: Loop might not exit
CREATE FUNCTION find_first_even(numbers integer[])
RETURNS integer AS $$
DECLARE
  i integer;
  num integer;
BEGIN
  FOREACH num IN ARRAY numbers LOOP
    IF num % 2 = 0 THEN
      RETURN num; -- This is good
    END IF;
  END LOOP;
  -- Missing RETURN if no even numbers found!
END;
$$ LANGUAGE plpgsql;

-- Fixed: Add RETURN after loop
CREATE FUNCTION find_first_even(numbers integer[])
RETURNS integer AS $$
DECLARE
  i integer;
  num integer;
BEGIN
  FOREACH num IN ARRAY numbers LOOP
    IF num % 2 = 0 THEN
      RETURN num;
    END IF;
  END LOOP;
  RETURN NULL; -- Added RETURN for no-match case
END;
$$ LANGUAGE plpgsql;

-- Problematic: RETURN after RAISE EXCEPTION
CREATE FUNCTION validate_age(age integer)
RETURNS boolean AS $$
BEGIN
  IF age < 0 THEN
    RAISE EXCEPTION 'Age cannot be negative';
  END IF;

  IF age > 150 THEN
    RAISE EXCEPTION 'Age seems unrealistic';
  END IF;

  RETURN true; -- This won't execute if exceptions are raised
END;
$$ LANGUAGE plpgsql;

-- Fixed: Return before raising exceptions
CREATE FUNCTION validate_age(age integer)
RETURNS boolean AS $$
BEGIN
  IF age < 0 THEN
    RAISE EXCEPTION 'Age cannot be negative';
    RETURN false; -- This line is unreachable!
  END IF;

  IF age > 150 THEN
    RAISE EXCEPTION 'Age seems unrealistic';
    RETURN false; -- This line is also unreachable!
  END IF;

  RETURN true;
END;
$$ LANGUAGE plpgsql;

-- Better: Structure without unreachable code
CREATE FUNCTION validate_age(age integer)
RETURNS boolean AS $$
BEGIN
  IF age < 0 OR age > 150 THEN
    RAISE EXCEPTION 'Invalid age: %', age;
  END IF;

  RETURN true;
END;
$$ LANGUAGE plpgsql;

-- Problematic: Using RETURN instead of RETURN NEXT
CREATE FUNCTION get_users_active_since(date)
RETURNS SETOF users AS $$
DECLARE
  user_record users%ROWTYPE;
BEGIN
  FOR user_record IN SELECT * FROM users WHERE last_active >= $1 LOOP
    RETURN user_record; -- Wrong: should be RETURN NEXT
  END LOOP;
  -- Missing RETURN; statement
END;
$$ LANGUAGE plpgsql;

-- Fixed: Using RETURN NEXT correctly
CREATE FUNCTION get_users_active_since(date)
RETURNS SETOF users AS $$
DECLARE
  user_record users%ROWTYPE;
BEGIN
  FOR user_record IN SELECT * FROM users WHERE last_active >= $1 LOOP
    RETURN NEXT user_record; -- Correct
  END LOOP;
  RETURN; -- Required to signal end of result set
END;
$$ LANGUAGE plpgsql;

-- Using RETURN QUERY
CREATE FUNCTION get_recent_orders(days integer)
RETURNS SETOF orders AS $$
BEGIN
  RETURN QUERY
    SELECT * FROM orders
    WHERE order_date > CURRENT_DATE - days;
  RETURN; -- Still needed after RETURN QUERY
END;
$$ LANGUAGE plpgsql;

-- Test function with various inputs
CREATE FUNCTION test_get_status() RETURNS void AS $$
BEGIN
  -- Test normal cases
  RAISE NOTICE 'Status 1: %', get_status(1);
  RAISE NOTICE 'Status 2: %', get_status(2);

  -- Test edge case that might miss RETURN
  RAISE NOTICE 'Status 999: %', get_status(999);

  -- Test NULL input
  RAISE NOTICE 'Status NULL: %', get_status(NULL);
END;
$$ LANGUAGE plpgsql;

-- Or use DO block for quick testing
DO $$
BEGIN
  PERFORM get_status(1);
  PERFORM get_status(2);
  PERFORM get_status(999); -- This might reveal missing RETURN
  PERFORM get_status(NULL);
EXCEPTION
  WHEN OTHERS THEN
    RAISE NOTICE 'Test failed: %', SQLERRM;
END;
$$;

-- Check function definition for completeness
SELECT prosrc FROM pg_proc WHERE proname = 'your_function_name';