MATLAB: Do I see an error when adding character data to a table

MATLAB

I have a table like the following:
x=[1;2;3];y=[4;5;6];T=table(x,y)
Then I add a column of placeholder values:
z=zeros(3,1);T=horzcat(T,table(z))
Now want to fill in the table with data from a serial port:
for i=1:3    T{i,'z'} = query(device,'command')    % or: T(i,'z') = query(device,'command')end
I get one of the following errors:
The value being assigned from must have 1 columns.
or
The number of table variables in an assignment must match.
How can I put this data in the table?

z=strings(3,1);T=horzcat(T,table(z))for i=1:3    T{i,'z'} = string(query(device,'command'))end