AdventureWorks Database: Look for rows where middlename is NULL
175. From the following table write a query in SQL to identify the rows with a middlename that is not NULL. Return businessentityid, persontype, firstname, middlename,and lastname. Sort the result set in ascending order on firstname.
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:
-- This SQL query selects specific columns from the person.person table, applying a condition to filter the results based on values in the MiddleName column.
-- Selecting columns: BusinessEntityID, PersonType, FirstName, MiddleName, and LastName.
SELECT businessentityid, persontype, firstname, middlename, lastname
-- From the person.person table.
FROM person.person
-- Filtering the results where the MiddleName column is not distinct from NULL.
WHERE middlename IS NOT DISTINCT FROM NULL
-- Ordering the results by the FirstName column in ascending order.
ORDER BY firstname;
Explanation:
- The query selects several columns from the person.person table: BusinessEntityID, PersonType, FirstName, MiddleName, and LastName.
- It filters the results to include only rows where the MiddleName column is not distinct from NULL.
- The IS NOT DISTINCT FROM operator is used to check for equality while treating NULL values as indistinct.
- Finally, the results are ordered by the FirstName column in ascending order.
- This query retrieves records from the person table where the MiddleName is either NULL or not NULL, considering them as equal, and orders the results alphabetically by FirstName.
Sample Output:
businessentityid|persontype|firstname |middlename|lastname |
----------------+----------+------------------------+----------+----------------------+
222|EM |A. Scott | |Wright |
15964|IN |Aaron | |Roberts |
15693|IN |Aaron | |Edwards |
2272|GC |Aaron | |Con |
17060|IN |Aaron | |Hernandez |
727|SC |Aaron | |Con |
16664|IN |Aaron | |Hill |
2306|GC |Aaron | |Nicholls |
5487|IN |Aaron | |Henderson |
5488|IN |Aaron | |Coleman |
5489|IN |Aaron | |Jenkins |
5491|IN |Aaron | |Perry |
5492|IN |Aaron | |Powell |
...
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