Du kan göra en korstabell med villkorlig aggregering:
SELECT
Item,
[X] = MAX(CASE WHEN [Columns] = 'X' THEN Result END),
[Y] = MAX(CASE WHEN [Columns] = 'Y' THEN Result END),
[Z] = MAX(CASE WHEN [Columns] = 'Z' THEN Result END)
FROM thisTable
GROUP BY Item