Database Reference
In-Depth Information
11.2.1.3
Statistical Distribution Functions
CUME_DIST(expression [, expression ... ]) WITHIN GROUP
(ORDER BY expression [, expression])
. The cumulative distribu-
tion of an expression within a group of values. A cumulative fre-
quency distribution is a plot of the number of observations falling
within or below an interval, a histogram. The cumulative distribution
function is the probability that a variable takes a value less than or
equal to a given value.
PERCENTILE_{ CONT | DISC }(expression) WITHIN GROUP
(ORDER BY expression)
. The percent point function or the inverse
distribution function for a
rete distribution.
Because the percent point function is an inverse distribution func-
tion, we start with the probability and compute the corresponding
value for the cumulative distribution.
CONT
inuous or a
DISC
11.2.1.4
Ranking Functions
RANK(expression [, expression ... ]) WITHIN GROUP
(ORDER BY expression [, expression])
. The rank of a value in a
group of values.
PERCENT_RANK(expression [, expression ... ]) WITHIN
GROUP (ORDER BY [, expression ... ])
. A cumulative distribution
ranking function. See
CUME_DIST
above.
DENSE_RANK(expression [, expression ... ]) WITHIN GROUP
(ORDER BY expression [, expression ... ])
. The rank of a row
within an ordered group of rows.
FIRST | LAST
(expression [, expression ... ]) WITHIN GROUP
(ORDER BY expression [, expression ... ])
. The first and last rank-
ing row in a sorted group of rows.
11.2.1.5
Grouping Functions
Grouping functions are used with analysis enhancements to define the slid-
ing window of data used for analysis.
GROUP_ID()
. Filters duplicate groupings from a query.
GROUPING(expression)
. Distinguishes between superset aggregate
rows and aggregate grouped rows.
