MySQL UNION Combining and merging data on different MySQL tables with the same columns into unique rows and running query
Example
This UNION ALL combines data from multiple tables and serve as a table name alias to use for your queries:
SELECT YEAR(date_time_column), MONTH(date_time_column), MIN(DATE(date_time_column)), MAX(DATE(date_time_column)), COUNT(DISTINCT (ip)), COUNT(ip), (COUNT(ip) / COUNT(DISTINCT (ip))) AS Ratio
FROM (
(SELECT date_time_column, ip FROM server_log_1 WHERE state = 'action' AND log_id = 150) UNION ALL
(SELECT date_time_column, ip FROM server_log_2 WHERE state = 'action' AND log_id = 150) UNION ALL
(SELECT date_time_column, ip FROM server_log_3 WHERE state = 'action' AND log_id = 150) UNION ALL
(SELECT date_time_column, ip FROM server_log WHERE state = 'action' AND log_id = 150)
) AS table_all
GROUP BY YEAR(date_time_column), MONTH(date_time_column);
