4 Replies Latest reply on Sep 29, 2018 10:41 AM by Jim Dehner

    Reason of Null Value

    Sean Wong

      Hi All,

       

      I am trying to learn how to use Tableau for my self-learning and I have a query regarding a pop up message on null value.

      It says month of review date axis has 1 null value

       

      Please refer to the below link:

       

      Tableau Public

       

      I am confused with the error as I have checked the excel data and there are no blanks in the 'review date' column, therefore why would there be a null value?

       

      Thanks!

        • 1. Re: Reason of Null Value
          Ritesh Bisht

          Hi Sean,

           

          I clicked on your data source tab of the workbook and found many null records (99k)

           

          Screen Shot 2018-09-29 at 10.00.03 PM.png

           

          Hence please recheck.

           

          Please mark the answer as CORRECT & HELPFUL if it has really helped you so that it can help others as well

           

          Ritesh

          • 2. Re: Reason of Null Value
            Jim Dehner

            Hi Sean

            see below - this is your data - filtered for NULL in the transaction date

             

            I could not open the data source tab - did you have more than one file that you connected together?

             

            that would produce something like this

             

             

            Jim

            If this posts assists in resolving the question, please mark it helpful or as the 'correct answer' if it resolves the question. This will help other users find the same answer/resolution.  Thank you.

            • 3. Re: Reason of Null Value
              Sean Wong

              Hi Jim,

               

              Yes, I have 2 sets of data.

                   #1 This is the audiobook sales data

                   #2 This is the audiobook review data

               

              ** Not all sales will have a review so I have connected sales data with review data through a left join

               

              For my report, I would like to see the number of reviews by month/year. Is the joining of the tables causing this null issue?

               

              Thanks

              • 4. Re: Reason of Null Value
                Jim Dehner

                probably the reason for your problem - you have records in one file that you are including but they have no corresponding record in the other file -

                so the measures from that you are bring in from the second file will show nulls in the "post joined file"

                 

                Jim

                If this posts assists in resolving the question, please mark it helpful or as the 'correct answer' if it resolves the question. This will help other users find the same answer/resolution.  Thank you.

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