Prøv denne forespørgsel:
SELECT line_no,
amount,
narration,
SUM( x ) OVER ( ORDER BY line_no
ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW
) as calc_group
FROM (
SELECT t.*,
CASE lag( narration ) OVER (order by line_no )
WHEN narration THEN 0
ELSE 1 END x
FROM test t
)
ORDER BY line_no
demo --> http://www.sqlfiddle.com/#!4/6d7aa /9