Question

I have a table as A (code,id,num,address)

Here code, id, and num are primary keys and no Foreign key dependency is present on any other table.

I need to update num using id… can I do that?

num was telephone number.i figurd this out.but i have another question

can we update the same column num using num only.example
UPDATE A
SET num = ”
WHERE num = ”;

Answer 1

UPDATE A
SET num = '<value>'
WHERE id = '<identifier>';

Should suffice, if I understand your question correctly.