With Cte As
(
	SELECT
		f.Code AS FruitCode
		,f.FRUIT
		,g.Code AS GrainCode
		,g.GRAIN
	FROM
	(
		(SELECT 
			ROW_NUMBER() OVER(PARTITION BY Code ORDER BY Fruit) RowNumber
			,Code
			,Fruit
		FROM PLC1_FRUITS) f
	    FULL JOIN 
		(SELECT 
			ROW_NUMBER() OVER(PARTITION BY Code ORDER BY Grain) RowNumber
			,Code
			,Grain
		FROM PLC1_GRAINS) g
	   ON f.Code = g.Code AND f.RowNumber = g.RowNumber
	)
)
SELECT 	
	b.Code
	,b.Name AS Bird
	,c.Grain
	,c.Fruit
FROM PLC1_BIRDS b
LEFT JOIN Cte c
ON b.Code = c.FruitCode
OR b.Code = c.GrainCode;

Tags: ROW_NUMBER(), FULL JOIN