SpirirHost Support Centre: MySQL Reference Manual p.208

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Table of Contents
1. General Information
2. MySQL Installation
3. Tutorial Introduction
4. Database Administration
5. MySQL Optimisation
6. MySQL Language Reference
7. MySQL Table Types
8. MySQL APIs
9. Extending MySQL

208 MySQL Technical Reference for Version 4.0.3 no host table entry matches, access is denied. If there is a match, the user's database- specic privileges are computed as the intersection (not the union!) of the privileges in the db and host table entries, that is, the privileges that are 'Y' in both entries. (This way you can grant general privileges in the db table entry and then selectively restrict them on a host-by-host basis using the host table entries.) After determining the database-specic privileges granted by the db and host table entries, the server adds them to the global privileges granted by the user table. If the result allows the requested operation, access is granted. Otherwise, the server checks the user's table and column privileges in the tables_priv and columns_priv tables and adds those to the user's privileges. Access is allowed or denied based on the result. Expressed in boolean terms, the preceding description of how a user's privileges are calcu- lated may be summarised like this: global privileges OR (database privileges AND host privileges) OR table privileges OR column privileges It may not be apparent why, if the global user entry privileges are initially found to be insucient for the requested operation, the server adds those privileges to the database-, table-, and column-specic privileges later. The reason is that a request might require more than one type of privilege. For example, if you execute an INSERT ... SELECT statement, you need both INSERT and SELECT privileges. Your privileges might be such that the user table entry grants one privilege and the db table entry grants the other. In this case, you have the necessary privileges to perform the request, but the server cannot tell that from either table by itself; the privileges granted by the entries in both tables must be combined. The host table can be used to maintain a list of secure servers. At TcX, the host table contains a list of all machines on the local network. These are granted all privileges. You can also use the host table to indicate hosts that are not secure. Suppose you have a machine public.your.domain that is located in a public area that you do not consider secure. You can allow access to all hosts on your network except that machine by using host table entries like this: +--------------------+----+- | Host | Db | ... +--------------------+----+- | public.your.domain | % | ... (all privileges set to 'N') | %.your.domain | % | ... (all privileges set to 'Y') +--------------------+----+- Naturally, you should always test your entries in the grant tables (for example, using mysqlaccess) to make sure your access privileges are actually set up the way you think they are. 4.2.11 Causes of Access denied Errors If you encounter Access denied errors when you try to connect to the MySQL server, the following list indicates some courses of action you can take to correct the problem:

MySQL Reference Manual

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