Description of the illustration approx_percentile.eps
APPROX_PERCENTILE( expr [ DETERMINISTIC ] [, { 'ERROR_RATE' | 'CONFIDENCE' } ] ) WITHIN GROUP ( ORDER BY expr [ DESC | ASC ] )
APPROX_PERCENTILE( expr [ DETERMINISTIC ] [, { 'ERROR_RATE' | 'CONFIDENCE' } ] ) WITHIN GROUP ( ORDER BY expr [ DESC | ASC ] )