<p>Hi guys,</p>
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<p>first of all: this forum is great. I'm new to Birt but learned alot here :-)</p>
<p>But one task I have at hand I cannot find a solution yet although I think it's not uncommon:</p>
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<p>I want to compare agregated sales numbers to the numbers of previous year.</p>
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<p>Example:</p>
<p>I have a db table with the following columns columns:</p>
<p>DateOfOrder | NumberOfSoldItems | Platform</p>
<p> </p>
<p>With that I made a crosstab so I can see the summarized NumberOfItems sold per Month and Platform.</p>
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<p>I now want to compare these NumberOfItems to the NumberOfItems of the same month of the last year and show the difference in the table cell.</p>
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<p>The user sets two report parameters: begindate and enddate</p>
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<p>Ii already tried to make 2 date sources with 2 their data sets: one giving the results of the sales within chosen begindate and enddate and another data set with the same parameters minus one year.</p>
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<p>Then I tried to combine these two datasets into one but I don't know at which level I can access the two NumberOfItems dates to compare/substract them.</p>
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<p>If someone could point me into the right direction it would be great, I'm trying and searching since days now...</p>
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<p>Thank you in advance!</p>
<p>Marc</p>
