Multiple joins at once

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Andy Varshneya

• November 05, 2015 16:00

Hi,

If I have multiple joins in the same join command, how will they be treated? Specifically, if I have an Inner Join and I'm joining a third sheet with an Outer Left Join, will the first Inner Join be the limiting factor? See http://i.imgur.com/gjWPPyU.png.

Thanks,
Andy

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  Joel Stewart

  • November 05, 2015 19:52

  Thanks for the question Andy! Both joins will be applied to the data set so yes, the inner join will limit results. Logically, the order of the joins does not matter -- the end result is the same in this case.

  In your example, there are three data sets: Set1, Set2 and Set3. Set1 and Set2 are inner joined on an ID column. Additionally Set2 is outer left joined to Set3 by ID.

  To build a full example, let's suppose this is in your data set which gives us full coverage of all possibilities of combinations of rows:

  Set1 - Animals:
  1, Ant
  3, Cougar
  5, Elephant
  7, Giraffe

  Set2 - RadioWords:
  1, Alpha
  2, Bravo
  3, Charlie
  4, Delta

  Set3 - Food:
  1, Apple
  2, Banana
  5, Egg
  6, Fries

  The expected output should contain the following data after performing your join:
  1, Ant, Alpha, Apple
  3, Cougar, Charlie, [null]

  Hope this helps!

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  Andy Varshneya

  • November 06, 2015 16:57

  Thanks Joel!

  Your explanation makes sense. Let me try it out.

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