What is the difference between inner join and join?

89 次查看(过去 30 天)
I have two tables, A and B. They are almost identical but in different sorted by rows.
I would like to tie them up by rows. Should I use innerjoin or join?
What is the difference between inner join and join? Thanks for any help.

采纳的回答

Jan
Jan 2018-1-12
编辑:Jan 2018-1-12
For a join both tables requires the same variables. For an innerjoin the overlapping variables are chosen.
A look into the documentation is useful:
help join
help innerjoin
You can create an innerjoin of:
a = table({'a' 'b' 'c' 'e' 'h'}', [1 2 3 11 17]', 'VariableNames',{'Key1' 'Var1'})
b = table({'a' 'b' 'd' 'e'}', [4 5 6 7]', 'VariableNames',{'Key1' 'Var2'})
The result contains the overlapping keys 'a', 'b', 'e' only. You cannot join them due to the not matching 'c' and 'h'. But you can join:
a = table({'a' 'b' 'c' 'e' 'h'}', [1 2 3 11 17]', 'VariableNames', {'Key1' 'Var1'})
b = table({'a' 'b' 'h' 'e' 'c'}', [4 5 6 7 8]', 'VariableNames', {'Key1' 'Var2'})
Here the join and innerjoin give the same results, so it does not matter, which one you run.
Note:
  • join: both tables need the same keys
  • innerjoin: The result contains the overlapping keys only
  • outerjoin: The result contains all keys of both tables and fills missing values with dummies.

更多回答(0 个)

类别

Help CenterFile Exchange 中查找有关 Tables 的更多信息

标签

产品

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by