Oracle / PLSQL: DENSE_RANK Function

This Oracle tutorial explains how to use the Oracle/PLSQL DENSE_RANK function with syntax and examples. 

Description 

The Oracle/PLSQL DENSE_RANK function returns the rank of a row in a group of rows. It is very similar to the RANK function. However, the RANK function can cause non-consecutive rankings if the tested values are the same. Whereas, the DENSE_RANK function will always result in consecutive rankings. 

The DENSE_RANK function can be used two ways - as an Aggregate function or as an Analytic function. 

DENSE_RANK Function Syntax #1 - Used as an Aggregate Function 

As an Aggregate function, the DENSE_RANK function returns the dense rank of a row within a group of rows. 

The syntax for the DENSE_RANK function when used as an Aggregate function is: DENSE_RANK( expression1, ... expression_n ) WITHIN GROUP ( ORDER BY expression1, ... expression_n )

Parameters or Arguments expression1 .. expression_n One or more expressions which identify a unique row in the group. 

Returns 

The DENSE_RANK function returns a numeric value. 

Note 

There must be the same number of expressions in the first expression list as there is in the ORDER BY clause. 

The expression lists match by position so the data types must be compatible between the expressions in the first expression list as in the ORDER BY clause. 

Applies To 

The DENSE_RANK function can be used in the following versions of Oracle/PLSQL: 

Oracle 12c, Oracle 11g, Oracle 10g, Oracle 9i 

Example (as an Aggregate Function) 

Let's look at some Oracle DENSE_RANK function examples and explore how to use the DENSE_RANK function in Oracle/PLSQL. 

For example: 

select DENSE_RANK(1000, 500) WITHIN GROUP (ORDER BY salary, bonus) 

from employees;

The SQL statement above would return the dense rank of an employee with a salary of $1,000 and a bonus of $500 from within the employees table. 

DENSE_RANK Function Syntax #2 - Used as an Analytic Function 

As an Analytic function, the DENSE_RANK function returns the rank of each row of a query with respective to the other rows. 

The syntax for the DENSE_RANK function when used as an Analytic function is: DENSE_RANK() OVER ( [ query_partition_clause] ORDER BY clause )

Returns 

The DENSE_RANK function returns a numeric value. 

Applies To 

The DENSE_RANK function can be used in the following versions of Oracle/PLSQL: 

Oracle 11g, Oracle 10g, Oracle 9i, Oracle 8i 

Example (as an Analytic Function) 

Let's look at some Oracle DENSE_RANK function examples and explore how to use the DENSE_RANK function in Oracle/PLSQL. 

For example: 

select employee_name, salary, 

DENSE_RANK() OVER (PARTITION BY department ORDER BY salary) 

from employees where department = 'Marketing';

The SQL statement above would return all employees who work in the Marketing department and then calculate a rank for each unique salary in the Marketing department. If two employees had the same salary, the DENSE_RANK function would return the same rank for both employees.