Analytic functions in the Oracle Database Context
function() over (partition by mycolumns order by mycolumns)
An analytic function takes place after that the original data set is retrieved.
The clause
defines how the function is calculated (aggregated for an aggregate function). For a sum for instance, the following statement:
SUM(MyColumn) over (partition by Year)
will do a sum by year (partition = group by).
If the PARTITION BY clause is absent, then the function is computed over the whole query result set.
List of analytic functions
On the HR sample schema.
SELECT j.job_title, COUNT(*),
MAX(salary) maxsalary,
MIN(salary) minsalary,
SUM(SUM(salary) over (), -- Grand Total Sum
RANK() OVER(ORDER BY MAX(salary)) rankorder
FROM employees e, jobs j
WHERE
e.job_id = j.job_id
GROUP BY j.job_title
ORDER BY rankorder;