Name
PERCENT_RANK
Synopsis
Generates a relative rank for a hypothetical row by dividing that row’s rank less 1 by the number of rows in the group.
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.
PERCENT_RANK(value_list
) WITHIN GROUP (ORDER BYsort_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 syntax:
PERCENT_RANK( ) 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 PERCENT_RANK aggregate function.
Example
The following example determines the percentage 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 1SELECT odd, PERCENT_RANK(4,1) WITHIN GROUP (ORDER BY num, odd)
FROM test4
GROUP BY odd;
ODD PERCENT_RANK(4,1)WITHINGROUP(ORDERBYNUM,ODD) ---------- -------------------------------------------- 0 1 1 .75
In group odd=0
, the new row comes after
(0,0)
, (2,0)
, and
(4,0)
, and thus it is position 4. The rank
computation is: (4th rank - 1)/3 rows = 100%
. In group ...
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