需求：今天遇到mysql中的日誌表需要設定最大儲存量、最多儲存天數，多餘的刪除

儲存過程程式碼如下：

 DELIMITER //
DROP PROCEDURE if exists log_system; 
CREATE PROCEDURE log_system (in u_n INT,u_d INT,s_n INT,s_d INT)//u_d使用者日誌天數，u_n使用者日誌數，s_n系統日誌數，s_d系統日誌天數
BEGIN
	 SET u_d = (SELECT userloggingDate FROM logging_prameter); //通過設定表得到使用者日誌天數
	 DELETE  FROM user_logging  
			WHERE time <= (select date_add(sysdate(),interval - u_d day) as yestoday);//通過演算法算出系統時間前去使用者日誌天數，得到應該刪除的時間點
	 IF (SELECT COUNT(*) FROM user_logging) > (SELECT userLoggingNumber FROM logging_prameter) THEN
		 SET u_n = (select COUNT(*) FROM user_logging)-(SELECT userLoggingNumber FROM logging_prameter);
		 DELETE FROM user_logging ORDER BY time LIMIT u_n;
	 END IF;
	
	SET s_d = (SELECT sysLoggingDate FROM logging_prameter); 
	DELETE  FROM sys_logging  WHERE time <= (select date_add(sysdate(),interval - s_d day) as yestoday);
	IF (SELECT COUNT(*) FROM sys_logging) > (SELECT sysLoggingNumber FROM logging_prameter) THEN
		 SET s_n = (select COUNT(*) FROM sys_logging)-(SELECT sysLoggingNumber FROM logging_prameter);
		 DELETE FROM sys_logging ORDER BY time LIMIT s_n;
	END IF;
END;
//DELIMITER
 

  DELIMITER //
    SET GLOBAL event_scheduler = ON;  
    DROP EVENT IF EXISTS `eventSysUserLogging`;  
    CREATE    EVENT IF NOT EXISTS `eventSysUserLogging`  
       
    ON SCHEDULE  
    EVERY 1 DAY   
     STARTS TIMESTAMP(CURRENT_DATE,'17:30:00')  
     ON COMPLETION PRESERVE ENABLE  
    DO  
        BEGIN  
            CALL log_system(@u_n,@u_n,@s_n,@s_d);//呼叫儲存過程
        END;  
// DELIMITER