Purpose
This function calculates the rank of a value within a set of values. When there are duplicate values in the sorted set, the same rank is assigned to these values, and the count of rows with the same value is recorded in the next rank. This function can be used as an aggregate or analytic function.
Note
- As an aggregate function,
RANKcalculates the rank of the assumed rows identified by the parameterexprrelative to the specified sorting specification. The parameter expressionexprand the expressions in theORDER BYclause of the aggregate function must match by position. Therefore, the number of parameters must be the same, and their data types must be compatible. - As an analytic function,
RANKcalculates the rank of each row returned by the query based on the values specified invalue_exprsand theorder_by_clause.
Syntax
/*Aggregate syntax*/
RANK(expr [, expr ]...) WITHIN GROUP
( ORDER BY
expr_col [ DESC | ASC ][ NULLS { FIRST | LAST } ]
[, expr_col [ DESC | ASC ][ NULLS { FIRST | LAST } ]]...
)
/*Analytic syntax*/
RANK() OVER ([ query_partition_clause ] order_by_clause)
Parameters
| Parameter | Description |
|---|---|
| expr | Specifies the value to query. |
| expr_col | Specifies the column name corresponding to the value to query. |
| DESC | ASC | Specifies the sorting order. This is an optional parameter.
|
| NULLS { FIRST | LAST } | Specifies the position of NULL values in expr_col after sorting. This is an optional parameter.
|
| OVER | Defines the window for calculation using the OVER clause. For more information, see Analytic Function Description. |
Return type
Returns the NUMBER data type.
Examples
Assume that the emp_msg table has been created.
obclient> SELECT * FROM emp_msg;
+--------+--------+------+------+
| DEPTNO | ENAME | SAL | MGR |
+--------+--------+------+------+
| 10 | CLARK | 2750 | 7839 |
| 10 | KING | 5300 | NULL |
| 10 | MILLER | 1600 | 7782 |
| 20 | ADAMS | 1400 | 7788 |
| 20 | FORD | 3300 | 7566 |
| 20 | JONES | 3275 | 7839 |
| 20 | SCOTT | 3300 | 7566 |
| 20 | SMITH | 1100 | 7902 |
| 30 | ALLEN | 1900 | 7698 |
| 30 | BLAKE | 3150 | 7839 |
| 30 | JAMES | 1250 | 7698 |
| 30 | MARTIN | 1550 | 7698 |
| 30 | TURNER | 1800 | 7698 |
| 30 | WARD | 1550 | 7698 |
| 30 | SCLARK | 1750 | 7839 |
+--------+--------+------+------+
15 rows in set
Aggregate function example
Returns the rank of 3300 in the sal column.
obclient> SELECT RANK(3300) WITHIN GROUP (ORDER BY sal) FROM emp_msg;
+-----------------------------------+
| RANK(3300)WITHINGROUP(ORDERBYSAL) |
+-----------------------------------+
| 13 |
+-----------------------------------+
1 row in set
Analytic function example
Groups by the deptno column and sorts the sal column in descending order, then returns the rank of each value in the sal column.
obclient> SELECT deptno,ename,sal,
RANK() OVER (PARTITION BY deptno ORDER BY sal DESC) "RANK"
FROM emp_msg;
+--------+--------+------+------+
| DEPTNO | ENAME | SAL | RANK |
+--------+--------+------+------+
| 10 | KING | 5300 | 1 |
| 10 | CLARK | 2750 | 2 |
| 10 | MILLER | 1600 | 3 |
| 20 | FORD | 3300 | 1 |
| 20 | SCOTT | 3300 | 1 |
| 20 | JONES | 3275 | 3 |
| 20 | ADAMS | 1400 | 4 |
| 20 | SMITH | 1100 | 5 |
| 30 | BLAKE | 3150 | 1 |
| 30 | ALLEN | 1900 | 2 |
| 30 | TURNER | 1800 | 3 |
| 30 | SCLARK | 1750 | 4 |
| 30 | MARTIN | 1550 | 5 |
| 30 | WARD | 1550 | 5 |
| 30 | JAMES | 1250 | 7 |
+--------+--------+------+------+
15 rows in set