How do I set a string field to NULL in phpmyadmin?

If I type NULL, it is treated as a string litera开发者_如何学编程l. If I leave it blank it is treated as an empty string.

There must be a checkbox near input for setting NULL value. ( only on nullable columns )

( alternatievly, I prefer to use SQL language directly )

In phpMyAdmin, there should be a checkbox next to the text field. Checking that should make the field NULL.

If you're using a query, it is:

UPDATE table SET field = NULL WHERE id = 4

Just tick the checkbox in the NULL column (and make sure that NULL is allowed for that field).