Page 25 - Open Soource Technologies 304.indd

Open Source Technologies

Notes These tables will become more important to you later in this unit as you add a few sample
users to My SQL. For now, just remember that these tables exist and must have relevant data in
them in order for users to complete actions. Further discussed in working with user privileges.

The Two-Step Authentication Process
As you’ve learned, My SQL checks three things during the authentication process. The actions
associated with these three things are performed in two steps:
1. My SQL looks at the host you are connecting from and the username and password pair
that you are using. If your host is allowed to connect, your password is correct for your
username, and the username matches one assigned to the host, My SQL moves to the
second step.
2. For whichever SQL command you are attempting to use, My SQL verifies that you have
the ability to perform that action for that database, table, and field.
If step 1 fails, you’ll see an error about it and you won’t be able to continue on to step 2. For
example, suppose you are connecting to My SQL with a username of joe and a password of
abc123 and you want to access a database called myDB. You will receive an error message if
any of those connection variables is incorrect for any of the following reasons:
Your password is incorrect.

Username joe doesn’t exist.
User joe can’t connect from localhost.

User joe can connect from localhost but cannot use the myDB database.
You may see an error like the following:
#/usr/local/My SQL/bin/My SQL -h localhost -u joe -pabc123 test

Error 1045: Access denied for user: ‘joe@localhost’ (Using password: YES)
If user joe with a password of abc123 is allowed to connect from localhost to the myDB database,
My SQL will check the actions that joe can perform in step 2 of the process. For our purposes,
suppose that joe is allowed to select data but is not allowed to insert data. The sequence of
events and errors would look like the following:
#/usr/local/My SQL/bin/My SQL -h localhost -u joe -pabc123 test

Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Welcome to the My SQL monitor. Commands end with ; or \g.

Your My SQL connection id is 61198 to server version: 4.0.21-log
Type ‘help;’ or ‘\h’ for help. Type ‘\c’ to clear the buffer.
My SQL> select * from test_table;

+——+——————+
| id | test_field |

+——+——————+
+——+——————+

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