WITH q AS
(
SELECT *, ROW_NUMBER() OVER (PARTITION BY parentID ORDER BY StartTime) AS rn
FROM mytable
)
SELECT qb.ParentID,
qb.StartTime AS BreakfastStart, qb.EndTime AS BreakfastEnd,
ql.StartTime AS LunchStart, ql.EndTime AS LunchEnd,
qd.StartTime AS DinnerStart, qd.EndTime AS DinnerEnd
FROM q qb
LEFT JOIN
q ql
ON ql.parentID = qb.parentID
AND ql.rn = 2
LEFT JOIN
q qd
ON qd.parentID = qb.parentID
AND qd.rn = 3
WHERE qb.rn = 1