You can select the column by using as below method.
When cursor is situated above the inserted table, shape of cursor is changed.
<Figure 1> Cursor shape to select the column
Single column can be selected by using the changed cursor shape.
<Figure 2> Selection of the single column
For selecting the multiple columns, move a mouse with pressing the mouse button.
<Figure 3> Selection of the multiple columns
Importance) It can't be selected in case of 'View as run mode'
Relate items)