AdventureWorks Database: Calculate the salary percentile for each employee within the 'Information Services' and 'Document Control' departments
SQL Query - AdventureWorks: Exercise-101 with Solution
101. From the following table write a query in SQL to calculate the salary percentile for each employee within the 'Information Services' and 'Document Control' departments. The query should return the department, last name, rate, cumulative distribution (CUME_DIST), and percent rank (PERCENT_RANK) of the rate. The result set should be ordered by department in ascending order and rate in descending order.
Sample table: HumanResources.vemployeedepartmenthistory
businessentityid|title|firstname |middlename |lastname |suffix|shift |department |groupname |startdate |enddate |
----------------+-----+-----------+----------------+-----------------+------+-------+--------------------------+------------------------------------+----------+----------+
1| |Ken |J |Sánchez | |Day |Executive |Executive General and Administration|2009-01-14| |
2| |Terri |Lee |Duffy | |Day |Engineering |Research and Development |2008-01-31| |
3| |Roberto | |Tamburello | |Day |Engineering |Research and Development |2007-11-11| |
4| |Rob | |Walters | |Day |Engineering |Research and Development |2007-12-05|2010-05-30|
4| |Rob | |Walters | |Day |Tool Design |Research and Development |2010-05-31| |
5|Ms. |Gail |A |Erickson | |Day |Engineering |Research and Development |2008-01-06| |
6|Mr. |Jossef |H |Goldberg | |Day |Engineering |Research and Development |2008-01-24| |
7| |Dylan |A |Miller | |Day |Research and Development |Research and Development |2009-02-08| |
8| |Diane |L |Margheim | |Day |Research and Development |Research and Development |2008-12-29| |
9| |Gigi |N |Matthew | |Day |Research and Development |Research and Development |2009-01-16| |
10| |Michael | |Raheem | |Day |Research and Development |Research and Development |2009-05-03| |
-- more --
Sample table: HumanResources.EmployeePayHistory
businessentityid|ratechangedate |rate |payfrequency|modifieddate |
----------------+-----------------------+-------+------------+-----------------------+
1|2009-01-14 00:00:00.000| 125.5| 2|2014-06-30 00:00:00.000|
2|2008-01-31 00:00:00.000|63.4615| 2|2014-06-30 00:00:00.000|
3|2007-11-11 00:00:00.000|43.2692| 2|2014-06-30 00:00:00.000|
4|2007-12-05 00:00:00.000| 8.62| 2|2007-11-21 00:00:00.000|
4|2010-05-31 00:00:00.000| 23.72| 2|2010-05-16 00:00:00.000|
4|2011-12-15 00:00:00.000|29.8462| 2|2011-12-01 00:00:00.000|
5|2008-01-06 00:00:00.000|32.6923| 2|2014-06-30 00:00:00.000|
6|2008-01-24 00:00:00.000|32.6923| 2|2014-06-30 00:00:00.000|
7|2009-02-08 00:00:00.000|50.4808| 2|2014-06-30 00:00:00.000|
8|2008-12-29 00:00:00.000|40.8654| 2|2014-06-30 00:00:00.000|
-- more --
Sample Solution:
-- Selecting Department, LastName, Rate, Cumulative Distribution (CUME_DIST), and Percent Rank (PERCENT_RANK)
SELECT Department, LastName, Rate,
CUME_DIST () OVER (PARTITION BY Department ORDER BY Rate) AS CumeDist,
PERCENT_RANK() OVER (PARTITION BY Department ORDER BY Rate) AS PctRank
-- From the vEmployeeDepartmentHistory view in the HumanResources schema, joining with EmployeePayHistory table
FROM HumanResources.vEmployeeDepartmentHistory AS edh
INNER JOIN HumanResources.EmployeePayHistory AS e
ON e.BusinessEntityID = edh.BusinessEntityID
-- Filtering the results for specific departments
WHERE Department IN ('Information Services','Document Control')
-- Ordering the results by Department and Rate in descending order
ORDER BY Department, Rate DESC;
Explanation:
- This SQL query retrieves data related to employee departments, including department name, employee last name, rate of pay, cumulative distribution (CUME_DIST), and percent rank (PERCENT_RANK) based on the rate of pay.
- The SELECT clause specifies the columns to be retrieved along with additional calculations for cumulative distribution and percent rank.
- The FROM clause indicates the source tables/views (vEmployeeDepartmentHistory and EmployeePayHistory) and their alias names (edh and e).
- The INNER JOIN statement joins the two tables/views based on the BusinessEntityID column.
- The WHERE clause filters the results to include only the specified departments ('Information Services' and 'Document Control').
- The PARTITION BY clause partitions the result set by department, allowing window functions to operate independently within each department.
- The ORDER BY clause orders the results first by department and then by rate of pay in descending order.
Sample Output:
department |lastname |rate |cumedist|pctrank | --------------------+-------------+-------+--------+------------------+ Document Control |Arifin |17.7885| 1.0| 1.0| Document Control |Kharatishvili|16.8269| 0.8| 0.5| Document Control |Norred |16.8269| 0.8| 0.5| Document Control |Chai | 10.25| 0.4| 0.0| Document Control |Berge | 10.25| 0.4| 0.0| Information Services|Trenary |50.4808| 1.0| 1.0| Information Services|Conroy |39.6635| 0.9|0.8888888888888888| Information Services|Ajenstat |38.4615| 0.8|0.6666666666666666| Information Services|Wilson |38.4615| 0.8|0.6666666666666666| Information Services|Sharma |32.4519| 0.6|0.4444444444444444| Information Services|Connelly |32.4519| 0.6|0.4444444444444444| Information Services|Bueno |27.4038| 0.4| 0.0| Information Services|Meyyappan |27.4038| 0.4| 0.0| Information Services|Bacon |27.4038| 0.4| 0.0| Information Services|Berg |27.4038| 0.4| 0.0|
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