MySQL in a Nutshell [32]
WHERE User LIKE 'paola';
+-------+--------------+
| User | Host |
+-------+--------------+
| paola | localhost |
| paola | caporale.com |
+-------+--------------+
DROP USER 'paola'@'localhost',
'paola'@'caporale.com';
Prior to version 5.0.2 of MySQL, the DROP USER statement won’t delete a user that has any privileges set to 'Y'. To eliminate the user account’s privileges, issue the REVOKE statement before using DROP USER:
REVOKE ALL ON *.* FROM 'paola'@'localhost';
DROP USER 'paola'@'localhost';
The ALL option is used to ensure revocation of all privileges. The *.* covers all tables in all databases. Prior to version 4.1.1 of MySQL, you would have to issue the following instead of a DROP USER statement:
DELETE FROM mysql.user
WHERE User='paola' AND Host='localhost';
FLUSH PRIVILEGES;
Notice that the FLUSH PRIVILEGES statement is necessary for the preceding DELETE statement to take effect immediately. It’s not necessary after the DROP USER statement, though.
Name
FLUSH
Synopsis
FLUSH [LOCAL|NO_WRITE_TO_BINLOG] option[, ...]
Options:
DES_KEY_FILE, HOSTS, LOGS, MASTER, PRIVILEGES, QUERY_CACHE,
STATUS, TABLE, TABLES, TABLES WITHOUT READ LOCK, USER_RESOURCES
Use this statement to clear and reload temporary caches in MySQL. It requires RELOAD privileges. To prevent this statement from writing to the binary log file, the NO_WRITE_TO_BINLOG flag or its LOCAL alias may be given. A particular cache to flush may be given as an option. Multiple options (see Table 4-1) may be given in a comma-separated list.
As of version 5.1 of MySQL, FLUSH cannot be used in stored functions and triggers, but can be used in stored procedures. As an alternative to the FLUSH statement, you can use the mysqladmin command (see Chapter 16).
Table 4-1. Options for FLUSH statement
Option
Explanation
DES_KEY_FILE
Reloads the DES encryption file, which is given with the --des-key-file option at startup or in the options file.
HOSTS
Clears the hosts cache, which is used to minimize host/IP address lookups. The hosts cache may need to be flushed if a host has been blocked from accessing the server.
LOGS
Used to close all of the log files and reopen them. If the server has binary logging enabled, it will change the binary log file to the next in numeric sequence. If the error log was enabled, it will rename the error log to the same name, but with the ending -old, and start a new error log. This option is not logged.
MASTER
This option is not logged and has been deprecated. Use the RESET MASTER statement instead.
PRIVILEGES
Reloads the grant tables for user privileges. This is necessary if the user table in the mysql database has been modified manually, without the GRANT statement.
QUERY CACHE
Instructs the server to defragment the query cache to improve performance. It doesn’t remove queries from cache, though. Use the RESET QUERY CACHE statement to remove the queries.
SLAVE
This option is not logged and has been deprecated. Use the RESET SLAVE statement instead.
STATUS
Resets the session values and counters for key caches to 0. The current thread’s session status variables are set to those of the global variables. The max_used_conections variable is set to the number of sessions open at the time.
TABLE[ table, ...]
Followed by one or more table names, this option forces the given tables to be closed. This will terminate any active queries on the given tables. Specified without any tables, the option has the same effect as TABLES.
TABLES
Causes all tables to be closed, all queries to be terminated, and the query cache to be flushed. This is the same as TABLE with no table name.
TABLES WITH READ LOCK
Closes all tables and locks them with a global read lock. This will allow users to view the data, but not to update it or insert records. The lock will remain in place until the UNLOCK TABLES statement is executed. This option is not logged.
USER_RESOURCES
Resets all user resource values that are calculated on an hourly basis. These are the values for the columns max_questions,