Although Cassandra doesn't have real NULL columns, CQL does provide some syntactic sugar to provide a more familiar interface to remove data from columns. You can, in fact, write UPDATE statements that set values to null:
UPDATE "users" SET "location" = NULL WHERE "username" = 'alice';
Note that this is purely syntactic sugar; the preceding statement is precisely the same operation as the following one:
DELETE "location" FROM "users" WHERE "username" = 'alice';
The DELETE form of the statement is more expressive of what we are actually doing—removing a value from a column—but the UPDATE form is more familiar to anyone used to working with SQL. Another advantage of the UPDATE statement is that we can write ...
