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SQL Puzzle – Correct the Incorrect Query – Win Price Worth USD 1000 – Aggregate and Subquery

Pinal Dave
SQL Puzzle
527 Comments

SQL Puzzle - Correct the Incorrect Query - Win Price Worth USD 1000 - Aggregate and Subquery puzzle It has been a while since we have seen a puzzle so let us do a small puzzle today. Actually, this is a very simple puzzle if you have worked with SQL Server for a while. I got an email from one of the readers from the blog post and he wanted me to correct the following query which he had written. Well, I have been working with SQL Server for over 19 years and I often do not remember the syntax and have to look up online. Here is a very simple puzzle for you which involves Aggregate and Subquery.

Important Update: The Workshop is now over and it was one of the landmark workshops, where I shared business secrets of successful Performance Tuning Expert. You can watch the recording of the workshop for a limited period of time.

Puzzle – Aggregate and Subquery

Here is the query when we run against the AdventureWorks database, it gives us an error. Remember AdventureWorks database is a sample database and you can download and install AdventureWorks over here.

USE AdventureWorks2014
GO
SELECT pch.StandardCost, p.ProductID
FROM Production.ProductCostHistory pch
INNER JOIN Production.Product p ON pch.ProductID = p.ProductID
WHERE pch.StandardCost > AVG(p.StandardCost)
GO

Now when you run the above query, it gives us the following error:

Msg 147, Level 15, State 1, Line 17
An aggregate may not appear in the WHERE clause unless it is in a subquery contained in a HAVING clause or a select list, and the column being aggregated is an outer reference.

Now here is your task, you need to help me to fix the above query. The hint to resolve the query is already in the blog post’s title and in the query error. You need to understand what my query is attempting to do and use the hint which is already pointed out to you. After you successfully fix the query it will produce the following results.

SQL Puzzle - Correct the Incorrect Query - Win Price Worth USD 1000 - Aggregate and Subquery correctresult

Rules

Well, there are no real rules, as long as you modify my query to get me above results. Please post your query in the comments section below before April 22, 2019. I will keep all the answers hidden till April 22, 2019 11:59:00 PM.

Winner

One Winner will get 1 free seat for my upcoming class, which is worth USD 1000.

SQL Server Performance Tuning Practical Workshop for EVERYONE
Date: April 23, 2019, Tuesday
8:00 AM Pacific Time | 11:00 AM Eastern Time

If you do not want to take part in the contest, you can directly register for the class here.

Update: April 23, 2019

The contest is closed and the winning Answer is here:

USE AdventureWorks2014
GO
SELECT pch.ProductID, pch.StartDate,pch.EndDate, pch.StandardCost, pch.ModifiedDate
FROM Production.ProductCostHistory pch
INNER JOIN Production.Product p ON pch.ProductID = p.ProductID
WHERE pch.StandardCost > p.StandardCost
GO

There is no need for the AVG on the StandardCost as there will be always a single entry for the product. Even if you change the query with group by + having you will still see the query uses the simple join.

Congratulations to the winner Nicholas Månsson. He is very excited to join the SQL Server Performance Tuning Practical Workshop for EVERYONE.

Everyone who participated you got to solve this difficult puzzle so indirectly you are a winner (of knowledge) as well. This was an intense competition with over 500 comments.

Reference: Pinal Dave (https://blog.sqlauthority.com)

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527 Comments. Leave new

  • Akshay R
    April 18, 2019 5:36 pm

    SELECT
    p.ProductID,
    StartDate,
    EndDate,
    pch.StandardCost,
    pch.ModifiedDate
    FROM Production.ProductCostHistory pch
    INNER JOIN Production.Product p
    ON pch.ProductID = p.ProductID
    WHERE pch.StandardCost > (select AVG(StandardCost) from Production.ProductCostHistory where ProductID = p.ProductID)
    and pch.StandardCost p.StandardCost

    Reply
  • Kapil
    April 18, 2019 5:37 pm

    USE AdventureWorks2014
    GO
    SELECT pch.StandardCost, p.ProductID
    FROM Production.ProductCostHistory pch
    INNER JOIN
    (
    Select ProductID,AVG(p.StandardCost) As StandardCost
    From Production
    Group By ProductID
    ) As m On m.ProductID = p.ProductID
    WHERE pch.StandardCost > m.StandardCost
    GO

    Reply
  • JK
    April 18, 2019 5:37 pm

    USE AdventureWorks2017
    GO
    SELECT pch.ProductID, pch.[StartDate], pch.[EndDate], pch.StandardCost, pch.ModifiedDate
    FROM Production.ProductCostHistory pch
    INNER JOIN Production.Product p ON pch.ProductID = p.ProductID
    WHERE pch.StandardCost > p.StandardCost
    GO

    Reply
  • Jim DuEst
    April 18, 2019 5:37 pm

    USE AdventureWorks2014
    GO
    SELECT pch.StandardCost, p.ProductID
    FROM Production.ProductCostHistory pch
    INNER JOIN (select prod.ProductID
    ,AVG(prod.StandardCost) as AvgStandardCost
    from Production.Product as prod
    group by prod.ProductID
    ) as p ON pch.ProductID = p.ProductID
    WHERE pch.StandardCost > p.AvgStandardCost
    GO

    Reply
  • Darren White
    April 18, 2019 5:37 pm

    Here’s my solution:

    USE AdventureWorks2014
    GO
    SELECT pch.StandardCost, p.ProductID
    FROM Production.ProductCostHistory pch
    INNER JOIN Production.Product p ON pch.ProductID = p.ProductID
    CROSS APPLY (SELECT AVG(p.StandardCost) avgStandardCost FROM Production.Product p GROUP BY p.ProductID WHERE pch.ProductID = p.ProductID) pAvg
    WHERE pch.StandardCost > pAvg.avgStandardCost
    GO

    Reply
  • Akshay R
    April 18, 2019 5:37 pm

    SELECT
    p.ProductID,
    StartDate,
    EndDate,
    pch.StandardCost,
    pch.ModifiedDate
    FROM Production.ProductCostHistory pch
    INNER JOIN Production.Product p
    ON pch.ProductID = p.ProductID
    WHERE pch.StandardCost > (select AVG(StandardCost) from Production.ProductCostHistory where ProductID = p.ProductID)
    and pch.StandardCost != p.StandardCost

    Reply
  • Roopesh Kumar
    April 18, 2019 5:38 pm

    Hi Pinal,
    Here is my query for the required result.

    SELECT p.ProductID, pch.StartDate, pch.EndDate, pch.StandardCost, pch.ModifiedDate
    FROM Production.ProductCostHistory pch
    INNER JOIN Production.Product p ON pch.ProductID = p.ProductID
    WHERE pch.StandardCost > (select AVG(prd.StandardCost) from Production.Product prd where prd.ProductID = p.ProductID)

    Thanks

    Reply
  • Tom Fish
    April 18, 2019 5:39 pm

    select pch.* –, DateBasedAvgStdCost
    from
    (
    SELECT StartDate, EndDate, AVG(pch.StandardCost) as DateBasedAvgStdCost
    FROM Production.ProductCostHistory pch
    INNER JOIN Production.Product p ON pch.ProductID = p.ProductID
    GROUP BY StartDate, EndDate
    ) a
    INNER JOIN Production.ProductCostHistory pch on a.StartDate = pch.StartDate and (a.EndDate = pch.EndDate or (a.EndDate IS NULL and pch.EndDate IS NULL))
    where pch.StandardCost > a.DateBasedAvgStdCost
    and pch.StartDate = ‘2012-05-30 00:00:00.000’ and pch.EndDate = ‘2013-05-29 00:00:00.000’
    ORDER BY 1

    I’m using AdventureWorks 2016. I think i have more rows. The question didn’t specify, but I did average standard cost per year. I didn’t think it was applicable to compare one year of individual cost to three years of average cost. But I didn’t have a customer to ask these questions. :-)

    Reply
  • Kapil
    April 18, 2019 5:39 pm

    USE AdventureWorks2014
    GO
    SELECT pch.StandardCost, m.ProductID
    FROM Production,ProductCostHistory pch
    INNER JOIN
    (
    Select ProductID,AVG(p.StandardCost) As StandardCost
    From Production As p
    Group By ProductID
    ) As m On m.ProductID = pch.ProductID
    WHERE pch.StandardCost > m.StandardCost
    GO

    Reply
  • Ritesh
    April 18, 2019 5:39 pm

    how can i send my query

    Reply
  • Ritesh
    April 18, 2019 5:40 pm

    SELECT pch.ProductID,
    pch.EndDate,
    pch.StandardCost,
    pch.ModifiedDate
    FROM Production.ProductCostHistory pch
    INNER JOIN (SELECT p.ProductID,
    AVG(p.StandardCost) AvgCost
    FROM Production.Product p
    GROUP BY p.ProductID) p
    ON p.ProductID = pch.ProductID
    WHERE pch.StandardCost > AvgCost

    Reply
  • Ashish K Srivastava
    April 18, 2019 5:41 pm

    USE AdventureWorks2014
    GO
    SELECT p.ProductID,
    pch.StartDate,
    pch.EndDate,
    pch.StandardCost,
    p.ModifiedDate
    FROM Production.ProductCostHistory pch
    INNER JOIN Production.Product p ON pch.ProductID = p.ProductID
    WHERE pch.StandardCost > (SELECT AVG(StandardCost) FROM Production.Product)
    GO

    Reply
  • salim ali
    April 18, 2019 5:45 pm

    oops, didn’t read the remit properly. here is my corrected soution

    SELECT
    p.ProductID,
    pch.StartDate,
    pch.EndDate,
    pch.StandardCost,
    pch.ModifiedDate
    FROM Production.ProductCostHistory pch
    INNER JOIN Production.Product p ON pch.ProductID = p.ProductID
    CROSS APPLY (SELECT AVG(StandardCost) AS StandardCostAvg
    FROM Production.Product
    WHERE Production.Product.ProductID = pch.ProductID

    ) avgCost
    WHERE pch.StandardCost > avgCost.StandardCostAvg
    GO

    Reply
  • Shobhit
    April 18, 2019 5:49 pm

    –Solution 1

    Select pch.StandardCost, p.ProductId
    From Production.ProductCostHistory pch
    Inner Join
    (
    Select ProductId,AVG(StandardCost) As AvgStandardCost From Production.Product
    Group By ProductId
    )p
    ON pch.ProductId=p.ProductId
    Where pch.StandardCost>p.AvgStandardCost

    –Solution 2

    ;WITH CTE
    AS
    (
    Select ProductId,AVG(StandardCost) As AvgStandardCost From Production.Product
    Group By ProductId
    )

    Select pch.StandardCost, p.ProductId
    From Production.ProductCostHistory pch
    Inner Join CTE p
    ON pch.ProductId=p.ProductId
    Where pch.StandardCost>p.AvgStandardCost

    Reply
  • Tiago Paim
    April 18, 2019 5:52 pm

    USE AdventureWorks2014
    GO
    SELECT pch.*
    FROM Production.ProductCostHistory pch
    WHERE pch.StandardCost > (select AVG(p.StandardCost) from Production.Product p where pch.ProductID = p.ProductID)
    GO

    Reply
  • Scott Williams
    April 18, 2019 5:52 pm

    USE AdventureWorks2014;
    GO
    SELECT pch.StandardCost,
    p.ProductID
    FROM Production.ProductCostHistory pch
    INNER JOIN Production.Product p ON pch.ProductID = p.ProductID
    GROUP BY pch.StandardCost,
    p.ProductID
    HAVING pch.StandardCost > AVG(p.StandardCost);
    GO

    Reply
  • Sanjay Kumar
    April 18, 2019 5:56 pm

    Hi Pinal,

    I have created the query in 4 different ways and also identified the query execution plan. Please see and verify the below query/details and let me know if anything wrong.

    Note: Only 1st query execution plan is difference (this is obvious) and will take time. Rest all are same.

    –1.
    SELECT p.ProductID, pch.StartDate, pch.EndDate, pch.StandardCost, pch.ModifiedDate
    FROM Production.ProductCostHistory pch WITH (NOLOCK)
    INNER JOIN Production.Product p WITH (NOLOCK) ON pch.ProductID = p.ProductID
    WHERE pch.StandardCost > (SELECT AVG(p.StandardCost) FROM Production.Product p WITH (NOLOCK) WHERE pch.ProductID = p.ProductID GROUP BY p.ProductID)

    –2.
    SELECT pch.ProductID, pch.StartDate, pch.EndDate, pch.StandardCost, pch.ModifiedDate
    FROM Production.ProductCostHistory pch WITH (NOLOCK)
    , (SELECT ProductID, AVG(StandardCost) AvgStandardCost FROM Production.Product WITH (NOLOCK) GROUP BY ProductID) p WHERE pch.ProductID = p.ProductID AND pch.StandardCost > p.AvgStandardCost

    –3.
    SELECT pch.ProductID, pch.StartDate, pch.EndDate, pch.StandardCost, pch.ModifiedDate
    FROM Production.ProductCostHistory pch WITH (NOLOCK)
    WHERE pch.StandardCost > (SELECT AVG(p.StandardCost) FROM Production.Product p WITH (NOLOCK) WHERE pch.ProductID = p.ProductID GROUP BY p.ProductID)

    –4.
    SELECT pch.ProductID, pch.StartDate, pch.EndDate, pch.StandardCost, pch.ModifiedDate FROM Production.ProductCostHistory pch WITH (NOLOCK)
    CROSS APPLY
    (SELECT AVG(p.StandardCost) AvgStandardCost FROM Production.Product p WITH (NOLOCK) WHERE pch.ProductID = p.ProductID GROUP BY p.ProductID) AS A WHERE pch.StandardCost>AvgStandardCost

    Thanks,
    Sanjay Kumar

    Reply
  • Joseph P Gollakner
    April 18, 2019 5:56 pm

    USE AdventureWorks2014
    GO

    SELECT
    p.ProductID
    , pch.StartDate
    , pch.EndDate
    , pch.StandardCost
    , pch.ModifiedDate
    FROM Production.ProductCostHistory pch
    INNER JOIN Production.Product p
    ON pch.ProductID = p.ProductID
    INNER JOIN (
    SELECT ProductID
    , AVG(StandardCost) AS AvgStandardCost
    FROM Production.Product
    GROUP BY ProductID
    ) avgStdCost
    ON avgStdCost.ProductID = p.ProductID
    WHERE pch.StandardCost > avgStdCost.AvgStandardCost

    GO

    Reply
  • Mark Marshall
    April 18, 2019 5:57 pm

    WITH CTE_Cost
    AS
    (
    SELECT ProductID, AVG(StandardCost) AS AvgCost
    FROM Production.Product
    GROUP BY ProductID
    )

    SELECT p.ProductID, pch.StartDate, pch.EndDate, pch.StandardCost, pch.ModifiedDate
    FROM Production.ProductCostHistory pch
    INNER JOIN CTE_Cost p ON pch.ProductID = p.ProductID
    WHERE pch.StandardCost > p.AvgCost

    Reply
  • Dave Abram
    April 18, 2019 5:57 pm

    USE AdventureWorks2014
    GO
    SELECT pch.StandardCost, p.ProductID
    FROM Production.ProductCostHistory pch
    INNER JOIN Production.Product p ON pch.ProductID = p.ProductID
    GROUP BY pch.StandardCost,
    p.ProductID
    HAVING pch.StandardCost > AVG(p.StandardCost)
    GO

    ….and the one below if you want it to look like the screenshot of your results;

    SELECT p.ProductID, pch.StartDate, pch.EndDate, pch.StandardCost, pch.ModifiedDate
    FROM Production.ProductCostHistory pch
    INNER JOIN Production.Product p ON pch.ProductID = p.ProductID
    GROUP BY p.ProductID,
    pch.StartDate,
    pch.EndDate,
    pch.StandardCost,
    pch.ModifiedDate
    HAVING pch.StandardCost > AVG(p.StandardCost)
    GO

    Reply
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Pinal Dave is an SQL Server Performance Tuning Expert and independent consultant with over 22 years of hands-on experience. He holds a Masters of Science degree and numerous database certifications.

Pinal has authored 14 SQL Server database books and 99 Pluralsight courses. To freely share his knowledge and help others build their expertise, Pinal has also written more than 5,800 database tech articles on his blog at https://blog.sqlauthority.com.

Pinal is an experienced and dedicated professional with a deep commitment to flawless customer service. If you need help with any SQL Server Performance Tuning Issues, please feel free to reach out at pinal@sqlauthority.com.

Pinal is also a CrossFit Level 1 Trainer (CF-L1) and CrossFit Level 2 Trainer (CF-L2).

Nupur Dave is a social media enthusiast and an independent consultant. She primarily focuses on the database domain, helping clients build short and long-term multi-channel campaigns to drive leads for their sales pipeline.

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