Check if ID exist in second table

I have 2 tables, now i want to check which numbers does not exist in the second table. So for example I have:

A = ["1","2","3"];
B = ["2","3"];

I want to check which number doesn't exist and keep that one.

So:

C = ["1"];

Answer 1

[David Hill]

A = ["1","2","3"];
B = ["2","3"];
C=A(~ismember(A,B))

C = "1"

[Dion Theunissen]

Now i have a list of double ID's.

C=bookings.id(~ismember(bookings.id(:),KopievanPolissenEuropeesche.VarName1(:)))

How can I use this to get only the table rows without common ID?