Mysql alter/write lock database I runned this in mysql:

UPDATE db SET Insert_priv='Y', Create_priv='Y' WHERE Db='wordpress_fixed';


But this not preventing from inserting more data to database wordpress_fixed. Is it supposed to work that way?
If you manually update any mysql.X table regarding privileges will require a FLUSH PRIVILEGES to effect the change.

Using GRANT is the better way of of ensuring privs exists (and doesn't require FLUSH PRIVILEGES).