AdventureWorks Database: Evaluate whether the values in two columns are the same

SQL Query - AdventureWorks: Exercise-129 with Solution

129. From the following table write a query in SQL to evaluate whether the values in the MakeFlag and FinishedGoodsFlag columns are the same.

productid|name                            |productnumber|makeflag|finishedgoodsflag|color       |safetystocklevel|reorderpoint|standardcost|listprice|size|sizeunitmeasurecode|weightunitmeasurecode|weight |daystomanufacture|productline|class|style|productsubcategoryid|productmodelid|sellstartdate          |sellenddate            |discontinueddate|rowguid                             |modifieddate           |
---------+--------------------------------+-------------+--------+-----------------+------------+----------------+------------+------------+---------+----+-------------------+---------------------+-------+-----------------+-----------+-----+-----+--------------------+--------------+-----------------------+-----------------------+----------------+------------------------------------+-----------------------+
        1|Adjustable Race                 |AR-5381      |false   |false            |            |            1000|         750|           0|        0|    |                   |                     |       |                0|           |     |     |                    |              |2008-04-30 00:00:00.000|                       |                |694215b7-08f7-4c0d-acb1-d734ba44c0c8|2014-02-08 10:01:36.827|
        2|Bearing Ball                    |BA-8327      |false   |false            |            |            1000|         750|           0|        0|    |                   |                     |       |                0|           |     |     |                    |              |2008-04-30 00:00:00.000|                       |                |58ae3c20-4f3a-4749-a7d4-d568806cc537|2014-02-08 10:01:36.827|
        3|BB Ball Bearing                 |BE-2349      |true    |false            |            |             800|         600|           0|        0|    |                   |                     |       |                1|           |     |     |                    |              |2008-04-30 00:00:00.000|                       |                |9c21aed2-5bfa-4f18-bcb8-f11638dc2e4e|2014-02-08 10:01:36.827|
        4|Headset Ball Bearings           |BE-2908      |false   |false            |            |             800|         600|           0|        0|    |                   |                     |       |                0|           |     |     |                    |              |2008-04-30 00:00:00.000|                       |                |ecfed6cb-51ff-49b5-b06c-7d8ac834db8b|2014-02-08 10:01:36.827|
      316|Blade                           |BL-2036      |true    |false            |            |             800|         600|           0|        0|    |                   |                     |       |                1|           |     |     |                    |              |2008-04-30 00:00:00.000|                       |                |e73e9750-603b-4131-89f5-3dd15ed5ff80|2014-02-08 10:01:36.827|
      317|LL Crankarm                     |CA-5965      |false   |false            |Black       |             500|         375|           0|        0|    |                   |                     |       |                0|           |L    |     |                    |              |2008-04-30 00:00:00.000|                       |                |3c9d10b7-a6b2-4774-9963-c19dcee72fea|2014-02-08 10:01:36.827|
      318|ML Crankarm                     |CA-6738      |false   |false            |Black       |             500|         375|           0|        0|    |                   |                     |       |                0|           |M    |     |                    |              |2008-04-30 00:00:00.000|                       |                |eabb9a92-fa07-4eab-8955-f0517b4a4ca7|2014-02-08 10:01:36.827|
	  -- more --

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Sample Solution:

-- Selecting specific columns from the Product table and applying a CASE statement to compare MakeFlag and FinishedGoodsFlag
SELECT 
    -- Selecting the ProductID column
    ProductID, 
    -- Selecting the MakeFlag column
    MakeFlag, 
    -- Selecting the FinishedGoodsFlag column
    FinishedGoodsFlag, 
    -- Applying a CASE statement to handle conditions based on MakeFlag and FinishedGoodsFlag
    CASE  
        -- If MakeFlag is equal to FinishedGoodsFlag, return NULL
        WHEN MakeFlag = FinishedGoodsFlag THEN NULL  
        -- If MakeFlag is not equal to FinishedGoodsFlag, return MakeFlag
        ELSE MakeFlag  
    END  
FROM 
    Production.Product  
-- Filtering records where ProductID is less than 10
WHERE 
    ProductID < 10;

Explanation:

• This SQL code selects specific columns from the Product table and applies a CASE statement to handle conditions based on MakeFlag and FinishedGoodsFlag.
• The CASE statement compares the values of MakeFlag and FinishedGoodsFlag for each row:
• If MakeFlag is equal to FinishedGoodsFlag, NULL is returned.
• If MakeFlag is not equal to FinishedGoodsFlag, MakeFlag itself is returned.
• The result set includes columns for ProductID, MakeFlag, and FinishedGoodsFlag, as well as the result of the CASE statement.
• Records are filtered to include only those where ProductID is less than 10.
• This SQL query can be used to identify products where MakeFlag and FinishedGoodsFlag are different, indicating potential inconsistencies in data or manufacturing status.

Sample Output:

productid|makeflag|finishedgoodsflag|makeflag|
---------+--------+-----------------+--------+
        1|false   |false            |        |
        2|false   |false            |        |
        3|true    |false            |true    |
        4|false   |false            |        |

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