AdventureWorks Database: Return the employee with the fewest number of vacation hours
SQL Query - AdventureWorks: Exercise-103 with Solution
103. From the following table write a query in SQL to return the employee with the fewest number of vacation hours compared to other employees with the same job title. Partitions the employees by job title and apply the first value to each partition independently.
Sample table: HumanResources.Employee
businessentityid|nationalidnumber|loginid |jobtitle |birthdate |maritalstatus|gender|hiredate |salariedflag|vacationhours|sickleavehours|currentflag|rowguid |modifieddate |organizationnode|
----------------+----------------+----------------------------+----------------------------------------+----------+-------------+------+----------+------------+-------------+--------------+-----------+------------------------------------+-----------------------+----------------+
1|295847284 |adventure-works\ken0 |Chief Executive Officer |1969-01-29|S |M |2009-01-14|true | 99| 69|true |f01251e5-96a3-448d-981e-0f99d789110d|2014-06-30 00:00:00.000|/ |
2|245797967 |adventure-works\terri0 |Vice President of Engineering |1971-08-01|S |F |2008-01-31|true | 1| 20|true |45e8f437-670d-4409-93cb-f9424a40d6ee|2014-06-30 00:00:00.000|/1/ |
3|509647174 |adventure-works\roberto0 |Engineering Manager |1974-11-12|M |M |2007-11-11|true | 2| 21|true |9bbbfb2c-efbb-4217-9ab7-f97689328841|2014-06-30 00:00:00.000|/1/1/ |
4|112457891 |adventure-works\rob0 |Senior Tool Designer |1974-12-23|S |M |2007-12-05|false | 48| 80|true |59747955-87b8-443f-8ed4-f8ad3afdf3a9|2014-06-30 00:00:00.000|/1/1/1/ |
5|695256908 |adventure-works\gail0 |Design Engineer |1952-09-27|M |F |2008-01-06|true | 5| 22|true |ec84ae09-f9b8-4a15-b4a9-6ccbab919b08|2014-06-30 00:00:00.000|/1/1/2/ |
6|998320692 |adventure-works\jossef0 |Design Engineer |1959-03-11|M |M |2008-01-24|true | 6| 23|true |e39056f1-9cd5-478d-8945-14aca7fbdcdd|2014-06-30 00:00:00.000|/1/1/3/ |
7|134969118 |adventure-works\dylan0 |Research and Development Manager |1987-02-24|M |M |2009-02-08|true | 61| 50|true |4f46deca-ef01-41fd-9829-0adab368e431|2014-06-30 00:00:00.000|/1/1/4/ |
8|811994146 |adventure-works\diane1 |Research and Development Engineer |1986-06-05|S |F |2008-12-29|true | 62| 51|true |31112635-663b-4018-b4a2-a685c0bf48a4|2014-06-30 00:00:00.000|/1/1/4/1/ |
9|658797903 |adventure-works\gigi0 |Research and Development Engineer |1979-01-21|M |F |2009-01-16|true | 63| 51|true |50b6cdc6-7570-47ef-9570-48a64b5f2ecf|2014-06-30 00:00:00.000|/1/1/4/2/ |
10|879342154 |adventure-works\michael6 |Research and Development Manager |1984-11-30|M |M |2009-05-03|true | 16| 64|true |eaa43680-5571-40cb-ab1a-3bf68f04459e|2014-06-30 00:00:00.000|/1/1/4/3/ |
-- more --
Sample table: Person.Person
businessentityid|persontype|namestyle|title|firstname |middlename |lastname |suffix|emailpromotion|additionalcontactinfo|demographics|rowguid |modifieddate |
----------------+----------+---------+-----+------------------------+----------------+----------------------+------+--------------+---------------------+------------+------------------------------------+-----------------------+
1|EM |false | |Ken |J |Sánchez | | 0| |[XML] |92c4279f-1207-48a3-8448-4636514eb7e2|2009-01-07 00:00:00.000|
2|EM |false | |Terri |Lee |Duffy | | 1| |[XML] |d8763459-8aa8-47cc-aff7-c9079af79033|2008-01-24 00:00:00.000|
3|EM |false | |Roberto | |Tamburello | | 0| |[XML] |e1a2555e-0828-434b-a33b-6f38136a37de|2007-11-04 00:00:00.000|
4|EM |false | |Rob | |Walters | | 0| |[XML] |f2d7ce06-38b3-4357-805b-f4b6b71c01ff|2007-11-28 00:00:00.000|
5|EM |false |Ms. |Gail |A |Erickson | | 0| |[XML] |f3a3f6b4-ae3b-430c-a754-9f2231ba6fef|2007-12-30 00:00:00.000|
6|EM |false |Mr. |Jossef |H |Goldberg | | 0| |[XML] |0dea28fd-effe-482a-afd3-b7e8f199d56f|2013-12-16 00:00:00.000|
7|EM |false | |Dylan |A |Miller | | 2| |[XML] |c45e8ab8-01be-4b76-b215-820c8368181a|2009-02-01 00:00:00.000|
8|EM |false | |Diane |L |Margheim | | 0| |[XML] |a948e590-4a56-45a9-bc9a-160a1cc9d990|2008-12-22 00:00:00.000|
9|EM |false | |Gigi |N |Matthew | | 0| |[XML] |5fc28c0e-6d36-4252-9846-05caa0b1f6c5|2009-01-09 00:00:00.000|
-- more --
Sample Solution:
-- Selecting the job title, last name, vacation hours, and the last name of the employee with the fewest vacation hours within each job title group
SELECT JobTitle, LastName, VacationHours,
FIRST_VALUE(LastName) OVER (PARTITION BY JobTitle -- Partitioning the data by job title
ORDER BY VacationHours ASC -- Ordering the data by vacation hours in ascending order
ROWS UNBOUNDED PRECEDING -- Specifying the window frame to include all preceding rows within the partition
) AS FewestVacationHours -- Calculating the last name of the employee with the fewest vacation hours
-- From the HumanResources.Employee table aliased as 'e' and joining with the Person.Person table aliased as 'p'
FROM HumanResources.Employee AS e
INNER JOIN Person.Person AS p
ON e.BusinessEntityID = p.BusinessEntityID
-- Ordering the results by job title
ORDER BY JobTitle;
Explanation:
- This SQL query retrieves the job title, last name, vacation hours, and the last name of the employee with the fewest vacation hours within each job title group.
- The SELECT clause specifies the columns to be retrieved, including additional calculations using window functions.
- The FROM clause indicates the source tables from which the data will be retrieved and joined.
- The INNER JOIN statement links the Employee table with the Person table based on the BusinessEntityID column.
- The PARTITION BY clause divides the result set into partitions based on the job title.
- The ORDER BY clause within the OVER clause orders the data within each partition by vacation hours in ascending order.
- The ROWS UNBOUNDED PRECEDING clause specifies the window frame to include all preceding rows within each partition.
- The FIRST_VALUE window function retrieves the first value within each partition, providing the last name of the employee with the fewest vacation hours.
Sample Output:
jobtitle |lastname |vacationhours|fewestvacationhours| ----------------------------------------+-----------------+-------------+-------------------+ Accountant |Moreland | 58|Moreland | Accountant |Seamans | 59|Moreland | Accounts Manager |Liu | 57|Liu | Accounts Payable Specialist |Tomic | 63|Tomic | Accounts Payable Specialist |Sheperdigian | 64|Tomic | Accounts Receivable Specialist |Poe | 60|Poe | Accounts Receivable Specialist |Spoon | 61|Poe | Accounts Receivable Specialist |Walton | 62|Poe | Application Specialist |Bueno | 71|Bueno | Application Specialist |Bacon | 72|Bueno | Application Specialist |Meyyappan | 73|Bueno | Application Specialist |Berg | 74|Bueno | ...
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