Learning Mysql

The wildcard approach typically removes the need to create multiple users, as a given user can connect from more than one machine. However, consider the case where the user steph wants to connect from the client hosts localhost
, steph.lloydhouse.com
, and steph.hughwilliams.com
. Using the techniques we’ve discussed so far, you have two choices have three users, one for each host or allow access from any host using 'steph'@'%'
. Neither solution is ideal. Fortunately, MySQL supports yet another way to create one user for different hosts, but this requires knowledge of the structure of the database tables used to manage the privilege system. We present this later in the chapter in Managing Privileges with SQL.”
Anonymous Users
We’ve previously seen how we can use wildcard specifications for hosts, but wildcard characters aren’t allowed in usernames you cant, for example, specify 'fred%'@'localhost'
. However, you can have a user with an empty username that allows anonymous connections and matches all usernames.
You can create an anonymous local user who can read data from the music database as follows:
mysql> GRANT SELECT ON music TO ''@'localhost';
Query OK, 0 rows affected (0.00 sec)
Note that the username is specified as two single quotes, with nothing between them.
This user allows you to connect without a username or password from the localhost
:
$ mysql
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 55 to server version 5.0.22-standard-log
Type 'help' or 'h' for help. Type 'c' to clear the buffer.
mysql>
You can use the
CURRENT_USER( function to check which user you’re logged in as:
mysql> SELECT CURRENT_USER();
+----------------+
| CURRENT_USER() |
+----------------+
| @localhost |
+----------------+
1 row inset sec)
Here, there is nothing before the symbol, indicating that you’re logged in as the anonymous user ''@localhost
. The MySQL server decides which user to log you in as based on a checklist we describe in the next section.

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