I am using mysql, I have table "wp_notification", here is the current structure of the table
id UserId PostId status 1 s:1:"8"; 26 accept
In the "UserId" column I saved the user's Userid in "array" format using the "serialize" function, but now I want to update (add one more user id in this column) this column So what do I do? Is it ok to just use mysql query?
You do not need to update this column. You can add another user ID in the future/current cell of this column.
However, it is worth noting that using "serialized" output strings as Ids in the database is not a good solution. See Normalization in MYSQL.