SELECT DISTINCT SCHEMA_NAME AS `database`
FROM information_schema.SCHEMATA
WHERE SCHEMA_NAME NOT IN ('information_schema', 'performance_schema', 'mysql')
ORDER BY SCHEMA_NAME
gets you a list of all the non-MYSQL databases on your system.
SELECT TABLE_SCHEMA AS `database`,
TABLE_NAME AS `table`
FROM information_schema.TABLES
WHERE TABLE_TYPE = 'BASE TABLE'
ORDER BY TABLE_SCHEMA, TABLE_NAME
gets you a list of all the actual tables (excluding SYSTEM VIEWs like the TABLES
table, and user-defined views) in all the databases.
Then, you should implement logic in your program to ensure that, for each database, it really is a Magento database before you truncate certain tables. Otherwise, you might become a despised person among your co-workers. :-)
Edit
Here's a stored procedure.
You need to edit it to do exactly what you need it to do; in particular, it counts rows rather than truncating tables, and it doesn't contain the correct list of log tables. (It would be irresponsible for me to publish such a wildly destructive stored procedure; you should edit it yourself to do the destructive part.)
DELIMITER $$
DROP PROCEDURE IF EXISTS `zap_magento_logs`$$
CREATE PROCEDURE `zap_magento_logs`()
BEGIN
-- declare variables for database and table names
DECLARE dbname VARCHAR(128) DEFAULT '';
DECLARE tbname VARCHAR(128) DEFAULT '';
DECLARE done INTEGER DEFAULT 0;
-- declare cursor for list of log tables
DECLARE log_table_list CURSOR FOR
SELECT TABLE_SCHEMA AS `database`,
TABLE_NAME AS `table`
FROM `information_schema`.TABLES
WHERE TABLE_TYPE = 'BASE TABLE'
AND TABLE_NAME IN
(
'log_customer',
'log_visitor',
'log_visitor_info',
'log_url',
'log_url_info',
'log_quote'
)
ORDER BY TABLE_SCHEMA, TABLE_NAME;
-- declare NOT FOUND handler
DECLARE CONTINUE HANDLER
FOR NOT FOUND SET done = 1;
OPEN log_table_list;
log_table: LOOP
FETCH log_table_list INTO dbname, tbname;
IF done = 1 THEN
LEAVE log_table;
END IF;
-- create an appropriate text string for a DDL or other SQL statement
SET @s = CONCAT('SELECT COUNT(*) AS num FROM ',dbname,'.',tbname);
PREPARE stmt FROM @s;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
END LOOP log_table;
CLOSE log_table_list;
END$$
DELIMITER ;
You run this by issuing the SQL command
CALL zap_magento_logs();