When a client connects to the MySQL server, the server uses the username provided by the client and the client host to select the appropriate account row from the mysql.user table. It then uses this row to authenticate the client. Before MySQL 5.5.7, the server authenticates the password provided by the client against the Password column of the account row. As of MySQL 5.5.7, the server authenticates clients using plugins. Selection of the proper account row from the mysql.user table is based on the user name and client host, as before, but the server authenticates the client credentials as follows: The server determines from the account row which authentication plugin applies for the client.
If the account row specifies no plugin name, the server uses native authentication; that is, authentication against the password stored in the Password column of the account row. This is the same authentication method provided by MySQL servers older than 5.5.7, before pluggable authentication was implemented, but now is implemented using two plugins that are built in and cannot be disabled. If the account row specifies a plugin, the server invokes it to authenticate the user. If the server cannot find the plugin, an error occurs. The plugin returns a status to the server indicating whether the user is permitted to connect.
Whereas SQL Server supports two authentication systems, Microsoft Access supports three. Unfortunately, three is not necessarily better than two, and the Access security system is not suited for large enterprise usage. The most commonly used is Database Password. A database password is simply a password that Access prompts you to type in when opening the database. A database can have only one password. You cannot assign a different password to different users.