The most difficult part here is not technical: it is about acknowledging their existence.
Regardless of how duplicates were created, the first step is to identify them within your data table.
#Data duplicacy how to
How to deal with possible duplicate entries in your data set? How to work around the problem of duplicates using SQL? Let me guide you through some of the techniques I have been using as a Data Analyst to identify, avoid and remove duplicates from any type of data set.īelow is the sample table (named customers) that I will use throughout this article to illustrate my points: Digging into the data, you suddenly realize that some customers were counted twice… which clearly questions your previous finding. Your conclusion seems to confirm your intuition: the number of clients has tripled over the past 12 months! You are so proud of this result - although somewhat surprised - that you want to double-check it before presenting it to your boss. You just conducted a brilliant analysis to evaluate how many clients you or your company acquired over the past year. This is why I want to share with you some lessons learned from my experience in dealing with duplicates using SQL. There are several reasons why some duplicates may appear in a data set, and a sanity check is often necessary before any analysis can be conducted properly. Duplicates are a recurring problem for any database user.
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