There are a couple of problems. c is a table, so
is also a table, with only one variable. A table is a container, so
isn't going to work, and even if it did,
wouldn't. You want
Then unique works, and == works. But wait, A.SAPID is a cell array of char, so == is still not going to work. As Scott suggests, you can use strcp. But I'd recommend using a string array for text data, not cell. It might be as simple as using "TextType","string" when you import data.
BUT ACTUALLY, values in SAPID appear to be drawn from a finite set of choices, in other words, they are categorical data. You probably should be using a categorical array.
A.SAPID = categorical(A.SAPID);
Then, all you need to do is iterate over categories(A.SAPID). == just works.
TurbineTest1 = A(A.SAPID==u(1),:);
BUT HANG ON. Do you really want maybe dozens of separate tables in your workspace? I strongly recommend that you look at things like groupsummary and rowfun to see if you can do operations on groups in your data without pulling it apart.