Replace n/a with NA for ALL columns postgreSQL : how do I update *ALL* columns of a table in psql? rather than doing them one column at a time.

    Table1
    Field1 | Field 2 | Field 3
    123    | 987     | n/a
    456    | n/a     | 101
    n/a    | abcdef  | n/a

So the output should be:

    Table1
    Field1 | Field 2 | Field 3
    123    | 987     | NA
    456    | NA      | 101
    NA     | abcdef  | NA

Note: Please give a psql query.