SQL query to compare product sales by month

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忘掉有多难
忘掉有多难 2021-02-10 07:45

I have a Monthly Status database view I need to build a report based on. The data in the view looks something like this:

Category | Revenue  |  Yearh  |  Month
B         


        
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  • 2021-02-10 08:19

    @Christian -- markdown editor -- UGH; especially when the preview and the final version of your post disagree... @Christian -- full outer join -- the full outer join is overruled by the fact that there are references to SP1 in the WHERE clause, and the WHERE clause is applied after the JOIN. To do a full outer join with filtering on one of the tables, you need to put your WHERE clause into a subquery, so the filtering happens before the join, or try to build all of your WHERE criteria onto the JOIN ON clause, which is insanely ugly. Well, there's actually no pretty way to do this one.

    @Jonas: Considering this:

    Also, the report is actually for financial year - so I would love to have empty columns with 0 in both if there was no sales in say month 5 for either 2007 or 2008.

    and the fact that this job can't be done with a pretty query, I would definitely try to get the results you actually want. No point in having an ugly query and not even getting the exact data you actually want. ;)

    So, I'd suggest doing this in 5 steps:
    1. create a temp table in the format you want your results to match
    2. populate it with twelve rows, with 1-12 in the month column
    3. update the "This Year" column using your SP1 logic
    4. update the "Last Year" column using your SP2 logic
    5. select from the temp table

    Of course, I guess I'm working from the assumption that you can create a stored procedure to accomplish this. You might technically be able to run this whole batch inline, but that kind of ugliness is very rarely seen. If you can't make an SP, I suggest you fall back on the full outer join via subquery, but it won't get you a row when a month had no sales either year.

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  • 2021-02-10 08:29

    The trick is to do a FULL JOIN, with ISNULL's to get the joined columns from either table. I usually wrap this into a view or derived table, otherwise you need to use ISNULL in the WHERE clause as well.

    SELECT 
        Program,
        Month,
        ThisYearTotalRevenue,
        PriorYearTotalRevenue
    FROM (
        SELECT 
            ISNULL(ThisYear.Program, PriorYear.Program) as Program,
            ISNULL(ThisYear.Month, PriorYear.Month),
            ISNULL(ThisYear.TotalRevenue, 0) as ThisYearTotalRevenue,
            ISNULL(PriorYear.TotalRevenue, 0) as PriorYearTotalRevenue
        FROM (
            SELECT Program, Month, SUM(TotalRevenue) as TotalRevenue 
            FROM PVMonthlyStatusReport 
            WHERE Year = @FinancialYear 
            GROUP BY Program, Month
        ) as ThisYear 
        FULL OUTER JOIN (
            SELECT Program, Month, SUM(TotalRevenue) as TotalRevenue 
            FROM PVMonthlyStatusReport 
            WHERE Year = (@FinancialYear - 1) 
            GROUP BY Program, Month
        ) as PriorYear ON
            ThisYear.Program = PriorYear.Program
            AND ThisYear.Month = PriorYear.Month
    ) as Revenue
    WHERE 
        Program = 'Bikes'
    ORDER BY 
        Month
    

    That should get you your minimum requirements - rows with sales in either 2007 or 2008, or both. To get rows with no sales in either year, you just need to INNER JOIN to a 1-12 numbers table (you do have one of those, don't you?).

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  • 2021-02-10 08:34

    About the markdown - Yeah that is frustrating. The editor did preview my HTML table, but after posting it was gone - So had to remove all HTML formatting from the post...

    @kcrumley I think we've reached similar conclusions. This query easily gets real ugly. I actually solved this before reading your answer, using a similar (but yet different approach). I have access to create stored procedures and functions on the reporting database. I created a Table Valued function accepting a product category and a financial year as the parameter. Based on that the function will populate a table containing 12 rows. The rows will be populated with data from the view if any sales available, if not the row will have 0 values.

    I then join the two tables returned by the functions. Since I know all tables will have twelve roves it's allot easier, and I can join on Product Category and Month:

    SELECT 
        SP1.Program,
        SP1.Year,
        SP1.Month,
        SP1.TotalRevenue AS ThisYearRevenue,
        SP2.TotalRevenue AS LastYearRevenue
    FROM GetFinancialYear(@Category, 'First Look',  2008) AS SP1 
         RIGHT JOIN GetFinancialYear(@Category, 'First Look',  2007) AS SP2 ON 
             SP1.Program = SP2.Program AND 
             SP1.Month = SP2.Month
    

    I think your approach is probably a little cleaner as the GetFinancialYear function is quite messy! But at least it works - which makes me happy for now ;)

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  • 2021-02-10 08:35

    The Case Statement is my best sql friend. You also need a table for time to generate your 0 rev in both months.

    Assumptions are based on the availability of following tables:

    sales: Category | Revenue | Yearh | Month

    and

    tm: Year | Month (populated with all dates required for reporting)

    Example 1 without empty rows:

    select
        Category
        ,month
        ,SUM(CASE WHEN YEAR = 2008 THEN Revenue ELSE 0 END) this_year
        ,SUM(CASE WHEN YEAR = 2007 THEN Revenue ELSE 0 END) last_year
    
    from
        sales
    
    where
        year in (2008,2007)
    
    group by
        Category
        ,month
    

    RETURNS:

    Category  |  Month  |  Rev. This Year  |  Rev. Last Year
    Bikes          1          10 000               0
    Bikes          2          12 000               11 000
    Bikes          3          12 000               11 500
    Bikes          4          0                    15 400
    

    Example 2 with empty rows: I am going to use a sub query (but others may not) and will return an empty row for every product and year month combo.

    select
        fill.Category
        ,fill.month
        ,SUM(CASE WHEN YEAR = 2008 THEN Revenue ELSE 0 END) this_year
        ,SUM(CASE WHEN YEAR = 2007 THEN Revenue ELSE 0 END) last_year
    
    from
        sales
        Right join (select distinct  --try out left, right and cross joins to test results.
                       product
                       ,year
                       ,month
                   from
                      sales --this ideally would be from a products table
                      cross join tm
                   where
                        year in (2008,2007)) fill
    
    
    where
        fill.year in (2008,2007)
    
    group by
        fill.Category
        ,fill.month
    

    RETURNS:

    Category  |  Month  |  Rev. This Year  |  Rev. Last Year
    Bikes          1          10 000               0
    Bikes          2          12 000               11 000
    Bikes          3          12 000               11 500
    Bikes          4          0                    15 400
    Bikes          5          0                    0
    Bikes          6          0                    0
    Bikes          7          0                    0
    Bikes          8          0                    0
    

    Note that most reporting tools will do this crosstab or matrix functionality, and now that i think of it SQL Server 2005 has pivot syntax that will do this as well.

    Here are some additional resources. CASE http://www.4guysfromrolla.com/webtech/102704-1.shtml SQL SERVER 2005 PIVOT http://msdn.microsoft.com/en-us/library/ms177410.aspx

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  • 2021-02-10 08:35

    Using pivot and Dynamic Sql we can achieve this result

    SET NOCOUNT ON
    IF OBJECT_ID('TEMPDB..#TEMP') IS NOT NULL
    DROP TABLE #TEMP
    
    ;With cte(Category , Revenue  ,  Yearh  ,  [Month])
    AS
    (
    SELECT 'Bikes', 10000, 2008,1 UNION ALL
    SELECT 'Bikes', 12000, 2008,2 UNION ALL
    SELECT 'Bikes', 12000, 2008,3 UNION ALL
    SELECT 'Bikes', 15000, 2008,1 UNION ALL
    SELECT 'Bikes', 11000, 2007,2 UNION ALL
    SELECT 'Bikes', 11500, 2007,3 UNION ALL
    SELECT 'Bikes', 15400, 2007,4
    )
    SELECT * INTO #Temp FROM cte
    
    Declare @Column nvarchar(max),
            @Column2 nvarchar(max),
            @Sql nvarchar(max)
    
    
    SELECT @Column=STUFF((SELECT DISTINCT ','+ 'ISNULL('+QUOTENAME(CAST(Yearh AS VArchar(10)))+','+'''0'''+')'+ 'AS '+ QUOTENAME(CAST(Yearh AS VArchar(10)))
    FROM #Temp order by 1 desc FOR XML PATH ('')),1,1,'')
    
    SELECT @Column2=STUFF((SELECT DISTINCT ','+ QUOTENAME(CAST(Yearh AS VArchar(10)))
    FROM #Temp FOR XML PATH ('')),1,1,'')
    
    SET @Sql= N'SELECT Category,[Month],'+ @Column +'FRom #Temp
                PIVOT
                (MIN(Revenue) FOR yearh IN ('+@Column2+')
                ) AS Pvt
    
                '
    EXEC(@Sql)
    Print @Sql
    

    Result

    Category    Month   2008    2007
    ----------------------------------
    Bikes       1       10000   0
    Bikes       2       12000   11000
    Bikes       3       12000   11500
    Bikes       4       0       15400
    
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  • 2021-02-10 08:40

    I could be wrong but shouldn't you be using a full outer join instead of just a left join? That way you will be getting 'empty' columns from both tables.

    http://en.wikipedia.org/wiki/Join_(SQL)#Full_outer_join

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