use the keyword LEFT OUTER JOIN to join two tables together and not loose any data from the left table, even those records that do not have a match in the right table.use the keyword INNER JOIN to join two tables together and only get the overlapping values.use the keyword UNION ALL to stack datasets with duplicate values.use the keyword UNION to stack datasets without duplicate values.To combine tables we will use the UNION, UNION ALL, INNER JOIN, LEFT OUTER JOIN and RIGHT OUTER JOIN keywords. Alternatively, you can create a new table that contains all the different details together in one dataset. By joining them together you are able to do some calculations. Particularly if there are different details in each table.
It is helpful to be able to combine data sets. Now that we know how to group and aggregate data in the table, this week we will learn how to join tables together. We did this using the GROUP BY keyword so that we could aggregate the statistics for each album. Last week we used data on the three albums released by the Spice Girls to determine which of the albums was the best. They only have a few weeks to catch up on, so it will be interesting to hear what they think. In the last couple weeks my parents have even decided to give my lessons a go. I am so proud of everyone’s efforts and how willing they have been to have a go at something new. We are learning data science as an online study group. Photo by Darius K on Unsplash Introductionįor the last 4 weeks my friends and I have been helping each other learn new skills while social distancing.
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