SELECT X,Y1 AS Y FROM TB1
UNION
SELECT X,Y2 FROM TB1
where y2 is not null
union
select X,Y3 FROM TB1
WHERE y3 is not null
UNION
SELECT X,Y2 FROM TB1
where y2 is not null
union
select X,Y3 FROM TB1
WHERE y3 is not null
UNION
SELECT X,Y2 FROM TB1 where y2 is not null
union
select X,Y3 FROM TB1 WHERE y3 is not null