How to merge two tables when the key variables are not common?

I have two tables A and B with key variables. Most variables are the same.

A = [X,Y,K;
  100,200,1;
  300,400,2;
  500,600,3]

B = [P,Q,K;
  1000,2000,1;
  3000,4000,2;
  5000,6000,3;
  7000,8000,4]

how could I get

C = [X,Y,K,P,Q;
  100,200,1,1000,2000;
  300,400,2,3000,4000;
  500,600,3,5000,6000;
  Nah,Nah,4,7000,8000]

Answer 1

[Guillaume]

This is called an outerjoin:

A = array2table([100 200 1; 300 400 2; 500 600 3], 'VariableNames', {'X', 'Y', 'K'});
B = array2table([1000 2000 1; 3000 4000 2; 5000 6000 3; 7000 8000 4], 'VariableNames', {'P', 'Q', 'K'});
C = outerjoin(A, B, 'MergeKeys', true)

Other types of joins are innerjoin and just plain join.

[Iris Li]

Thank you very much! Just one thing.. how could I decide the key variable when I have multiple variable names in both A and B like K1, K2 and K3?

[Iris Li]

In fact I have identical variable names in A and B... But have to match by K1

[Guillaume]

It's all documented in the link I provided, you can provide the keys with the Keys, LeftKeys, or RightKeys optional arguments.

[Iris Li]

Thank you!!!