All language subtitles for 3. Preparing the data

To practice on joins will be creating a separate data set of two tables, let us see how to create
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these two tables.
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The first table will be from the sales table, and it will contain only those records where ship date
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lies between 1st January 2015 and 21st December 2015.
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So this table will be named as sales_2015 as this sales of year 2015. The second table
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we are creating is of customers whose ages between 20 and 60.
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The name of this table will be customer_20_60, and it will be part of the customer table were
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aged between 20 and 60. For the first table
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The count of rows will be 2131. This you can check by running this check query.
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And the number of distinct customers were purchasing in year 2015 is 578, This you can check using this second count
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query in our customer table where customers are aged between 20 and 60, the count of customers is 597.
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Some of the customers will be presenting both the tables.
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Some will be present in only sales table and not in the second customer table.
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Some will be present in the customer table and not in sales table.
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This is what we wanted to create so that we can clearly see the difference between all these types of
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joins, I'm copying these two queries into a text file and attaching it to the resources section of
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the lecture.
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You can copy paste these queries to run them.
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I'm not discussing these queries in depth because we have not discussed subquery, which will be in
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the later part of this course.
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Next, we will discuss the inner join.