The command table-insert-column inserts a column of cells to
the left of the current row in a table. This pushes the current
column to the right. To insert a column to the right side of the
rightmost column, place point to the right of the rightmost column,
which is outside of the table, prior to invoking this command. A
numeric prefix argument specifies the number of columns to insert.
A command table-delete-column deletes a column of cells at
point. A numeric prefix argument specifies the number of columns to
delete.