Aggregate Syntax
dense_rank_aggregate::=
Analytic Syntax
dense_rank_analytic::=
See Also:
Analytic Functions for information on syntax, semantics, and restrictions
Purpose
DENSE_RANK
computes the rank of a row in an ordered group of rows and returns the rank as a NUMBER
. The ranks are consecutive integers beginning with 1. The largest rank value is the number of unique values returned by the query. Rank values are not skipped in the event of ties. Rows with equal values for the ranking criteria receive the same rank. This function is useful for top-N and bottom-N reporting.
This function accepts as arguments any numeric data type and returns NUMBER
.
As an aggregate function, DENSE_RANK
calculates the dense rank of a hypothetical row identified by the arguments of the function with respect to a given sort specification. The arguments of the function must all evaluate to constant expressions within each aggregate group, because they identify a single row within each group. The constant argument expressions and the expressions in the order_by_clause
of the aggregate match by position. Therefore, the number of arguments must be the same and types must be compatible.
As an analytic function, DENSE_RANK
computes the rank of each row returned from a query with respect to the other rows, based on the values of the value_exprs
in the order_by_clause
.
See Also:
Appendix C in Oracle Database Globalization Support Guide for the collation determination rules, which define the collation DENSE_RANK
uses to compare character values for the ORDER
BY
clause
Aggregate Example
The following example computes the ranking of a hypothetical employee with the salary $15,500 and a commission of 5% in the sample table oe.employees
:
SELECT DENSE_RANK(15500, .05) WITHIN GROUP (ORDER BY salary DESC, commission_pct) "Dense Rank" FROM employees; Dense Rank ---------- 3
Analytic Example
The following statement ranks the employees in the sample hr
schema in department 60 based on their salaries. Identical salary values receive the same rank. However, no rank values are skipped. Compare this example with the analytic example for RANK.
SELECT department_id, last_name, salary, DENSE_RANK() OVER (PARTITION BY department_id ORDER BY salary) DENSE_RANK FROM employees WHERE department_id = 60 ORDER BY DENSE_RANK, last_name; DEPARTMENT_ID LAST_NAME SALARY DENSE_RANK ------------- ------------------------- ---------- ---------- 60 Lorentz 4200 1 60 Austin 4800 2 60 Pataballa 4800 2 60 Ernst 6000 3 60 Hunold 9000 4