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AdventureWorks Database: Return only rows that have a count of employees by title

SQL Query - AdventureWorks: Exercise-180 with Solution

180. From the following tables write a query in SQL to return only the rows that have a count of employees by title. Filter the results by department ID 12 or 14. Return name, jobtitle, grouping level and employee count.

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 --

Click to view Full table

Sample table: HumanResources.EmployeeDepartmentHistory

businessentityid|departmentid|shiftid|startdate |enddate   |modifieddate           |
----------------+------------+-------+----------+----------+-----------------------+
               1|          16|      1|2009-01-14|          |2009-01-13 00:00:00.000|
               2|           1|      1|2008-01-31|          |2008-01-30 00:00:00.000|
               3|           1|      1|2007-11-11|          |2007-11-10 00:00:00.000|
               4|           1|      1|2007-12-05|2010-05-30|2010-05-28 00:00:00.000|
               4|           2|      1|2010-05-31|          |2010-05-30 00:00:00.000|
               5|           1|      1|2008-01-06|          |2008-01-05 00:00:00.000|
               6|           1|      1|2008-01-24|          |2008-01-23 00:00:00.000|
			   -- more --

Click to view Full table

Sample table: HumanResources.Department

departmentid|name                      |groupname                           |modifieddate           |
------------+--------------------------+------------------------------------+-----------------------+
           1|Engineering               |Research and Development            |2008-04-30 00:00:00.000|
           2|Tool Design               |Research and Development            |2008-04-30 00:00:00.000|
           3|Sales                     |Sales and Marketing                 |2008-04-30 00:00:00.000|
           4|Marketing                 |Sales and Marketing                 |2008-04-30 00:00:00.000|
           5|Purchasing                |Inventory Management                |2008-04-30 00:00:00.000|
           6|Research and Development  |Research and Development            |2008-04-30 00:00:00.000|
           7|Production                |Manufacturing                       |2008-04-30 00:00:00.000|
           8|Production Control        |Manufacturing                       |2008-04-30 00:00:00.000|
           9|Human Resources           |Executive General and Administration|2008-04-30 00:00:00.000|
          10|Finance                   |Executive General and Administration|2008-04-30 00:00:00.000|
          11|Information Services      |Executive General and Administration|2008-04-30 00:00:00.000|
          12|Document Control          |Quality Assurance                   |2008-04-30 00:00:00.000|
          13|Quality Assurance         |Quality Assurance                   |2008-04-30 00:00:00.000|
          14|Facilities and Maintenance|Executive General and Administration|2008-04-30 00:00:00.000|
          15|Shipping and Receiving    |Inventory Management                |2008-04-30 00:00:00.000|
          16|Executive                 |Executive General and Administration|2008-04-30 00:00:00.000|

Click to view Full table

Sample Solution:

-- Selecting the department name and employee job title
SELECT D.Name  
    ,E.JobTitle  
    -- Creating a grouping level column to identify the level of aggregation
    ,GROUPING(D.Name, E.JobTitle) AS "Grouping Level"  
    -- Counting the number of employees in each group
    ,COUNT(E.BusinessEntityID) AS "Employee Count"  
-- Selecting from the Employee table
FROM HumanResources.Employee AS E  
    -- Joining with the EmployeeDepartmentHistory table
    INNER JOIN HumanResources.EmployeeDepartmentHistory AS DH  
        ON E.BusinessEntityID = DH.BusinessEntityID  
    -- Joining with the Department table
    INNER JOIN HumanResources.Department AS D  
        ON D.DepartmentID = DH.DepartmentID       
-- Filtering out records where the end date is not null
WHERE DH.EndDate IS NULL  
    -- Filtering out records where the department ID is either 12 or 14
    AND D.DepartmentID IN (12,14)  
-- Grouping the results by department name and employee job title, with rollup for subtotal calculations
GROUP BY ROLLUP(D.Name, E.JobTitle)
-- Filtering out groups where the grouping level is 0 (grand total level)
HAVING GROUPING(D.Name, E.JobTitle) = 0;

Explanation:

  • This SQL query is similar to the previous one but with a different condition in the HAVING clause.
  • Comments are added to explain each part of the query for better understanding and maintenance.
  • Here's a breakdown of what the query does:
    • It selects the department name, employee job title, a grouping level indicator, and the count of employees.
    • It joins the Employee table with the EmployeeDepartmentHistory table and the Department table to get the necessary information about employees and their departments.
    • It filters out records where the end date of the employee's department history is not null, indicating the current department.
    • It further filters out records where the department ID is either 12 or 14, focusing only on specific departments.
    • It groups the results by department name and employee job title, with rollup used for subtotal calculations.
    • It applies a having clause to filter out groups where the grouping level is 0, indicating the grand total row.

Sample Output:

name                      |jobtitle                           |Grouping Level|Employee Count|
--------------------------+-----------------------------------+--------------+--------------+
Document Control          |Control Specialist                 |             0|             2|
Facilities and Maintenance|Janitor                            |             0|             4|
Facilities and Maintenance|Facilities Manager                 |             0|             1|
Document Control          |Document Control Assistant         |             0|             2|
Document Control          |Document Control Manager           |             0|             1|
Facilities and Maintenance|Maintenance Supervisor             |             0|             1|
Facilities and Maintenance|Facilities Administrative Assistant|             0|             1|

SQL AdventureWorks Editor:

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