How to add comment for row table

[yzxbshi]

create table testdb.foobar (a string with 'column 1', b string not null with 'column 2') using row;

It's error when I execute the sql. so I tried to add a comment like pg database, It also reported an error.

COMMENT ON COLUMN "test_db"."foobar"."a" IS 'column 1';