How to extract a column (or a row) of a matrix as another column vector/ column matrix (or a row vector), not as a list?

Question

Suppose I have a matrix 'mat' as

mat = Table[Subscript[m, i, j], {i, 5}, {j, 5}];
mat // MatrixForm

I want to extract the first column (or any row) as

a = mat[[All, 1]]

{Subscript[m, 1, 1], Subscript[m, 2, 1], Subscript[m, 3, 1], \
Subscript[m, 4, 1], Subscript[m, 5, 1]}

But I want the output as

{{Subscript[m, 1, 1]}, {Subscript[m, 2, 1]}, {Subscript[m, 3, 
  1]}, {Subscript[m, 4, 1]}, {Subscript[m, 5, 1]}}

How can I do that?

Answer 1

a = mat[[All, {1}]]

{{Subscript[m, 1, 1]}, {Subscript[m, 2, 1]}, {Subscript[m, 3, 1]},
  {Subscript[m, 4, 1]}, {Subscript[m, 5, 1]}}

MatrixForm  @ a

Answer 2

Try Partition[mat[[All, 1]], 1].