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Hi Folks,
I am stumped.
I am trying to merge two tables into a new table using a LEFT JOIN. Both tables have unique records on each row. When I join the tables, BI creates duplicate rows on some records for no apparent reason. The duplicates are identical in every way.
Can anybody explain this? Is this a bug?
Solved! Go to Solution.
The problem lay with the Data.
The LEFT JOIN functionality of PowerBI works perfectly.
Hi @DataGuy2016,
If you haven't already found a solution...
I had a similar issue where LEFT JOIN was creating duplicates, resulting over 1000 rows of data where I should have just 85.
I solved the issue by expanding the relative columns as an aggregate, instead of just an expansion.
Hope that this makes sense.
I am having the same problem with my data. And no, I do not understand your answer to "expand as an aggregate," will you please clarify?
I know this is an old thread, but if someone else is still reading this thread and would like to offer help, I appreciate it!
HI JR,
Thank you for the response. Could you send me an email at trossgreene@stormsmart.com. I want to talk with you more and share a sample file, but I can't figure out how to upload an excel file here.
Thanks,
Tera
Hi @Anonymous,
I have created a quick sample that I hope helps explain my method. It may not work with your data, but it did fix the issue with mine!
I have two tables, I would like to merge 'Customer Type' with 'Customer Name'.
Customer Name Table
Customer Type Table
I would like to merge using the 'ID' column in both, to bring in the 'Cust Type' field from table 'Customer Type' into table 'Customer Name'.
Merge Options
Once successfully merged, I see the below:
I now have the option to expand that column of the merged table to bring in data from the 'Customer Type' table. But this is where I choose to Aggregate a field rather than expand. You may require a different aggregate measure other than median, dependant on data type:
Expand as Aggregate
The result from my data is below:
Result
Please also see sample.pbix file which I hope can help you with your issue.
Hi,
The LEFT JOIN table Merge is creating duplicate records from the LHS table.
I understand what a LEFT JOIN is.
My LHS table only has unique rows. Why is PowerBI creating duplicate records? These are 100% identical in every respect.
SQL JOINS