SQL in a Nutshell, 2nd Edition

Name

CUME_DIST

Synopsis

Computes the relative rank of a hypothetical row within a group of rows, where that relative rank is computed as follows:

(rows_preceding_hypothetical + rows_peered_with_hypothetical) /rows_in_group

Bear in mind that the rows_in_group value includes the hypothetical row that you are proposing when you call the function.

SQL2003 Syntax

In the following syntax, items in the value_list correspond by position to items in the sort_list. Therefore, both lists must have the same number of expressions.

CUME_DIST(value_list) WITHIN GROUP (ORDER BY sort_list)
value_list ::= expression [,expression...]
sort_list ::= sort_item [,sort_item...]
sort_item ::= expression [ASC|DESC] [NULLS FIRST|NULLS LAST]

Oracle

Oracle follows the SQL2003 syntax and implements the following analytic syntax:

CUME_DIST OVER ([partioning] ordering )

For an explanation of the partioning and order clauses, see the section later in this chapter titled Section 4.3.

DB2, MySQL, PostgreSQl, and SQL Server

These platforms do not implement the CUME_DIST aggregate function.

Example

The following example determines the relative rank of the hypothetical new row (num=4, odd=1) within each group of rows from test4, where groups are distinguished by the values in the odd column:

SELECT * FROM test4;
       NUM        ODD
---------- ----------
         0          0
         1          1
         2          0
         3          1
         3          1
         4          0
         5          1
SELECT odd, CUME_DIST(4,1) WITHIN GROUP (ORDER BY num, odd)
FROM test4
GROUP BY odd; ODD CUME_DIST(4,1)WITHINGROUP(ORDERBYNUM,ODD) ---------- ----------------------------------------- ...