mysql的存儲過程、游標 、事務實例詳解

DELIMITER $$
DROP PROCEDURE IF EXISTS `transferEmailTempData`$$

CREATE PROCEDURE transferEmailTempData(IN jobId VARCHAR(24))
BEGIN
  DECLARE idval VARCHAR(24) DEFAULT '';
  DECLARE taskIdval VARCHAR(24) DEFAULT '';
  DECLARE groupIdval VARCHAR(24) DEFAULT '';
  DECLARE emailval VARCHAR(50) DEFAULT '';
  
  /*標識正式表是否存在一條相同數(shù)據(jù)，即：groupId、email相同*/
  DECLARE infoId VARCHAR(24) DEFAULT '';
  
  /*標識事務錯誤*/
  DECLARE err INT DEFAULT 0;
  
  /*達到一定數(shù)量就進行提交，計數(shù)器*/
  DECLARE counts INT DEFAULT 0;
  
  /*標識是否回滾過*/
  DECLARE isrollback INT DEFAULT 0;
  
  /*游標遍歷時，作為判斷是否遍歷完全部記錄的標記*/
  DECLARE done INTEGER DEFAULT 0;
  
  /*獲取臨時表該任務的數(shù)據(jù)*/
  DECLARE cur CURSOR FOR SELECT id,taskId,groupId,email FROM `t_email_data_temp` WHERE taskId=jobId;
  
  /*根據(jù)群組id、email查詢是否存在相同記錄*/
  DECLARE cur2 CURSOR FOR SELECT id FROM `t_email_info` e WHERE e.`group_id` = groupIdval AND e.`email_address` = emailval; 
  
  /* 出現(xiàn)錯誤，設置為1，只要發(fā)生異常就回滾*/
  DECLARE CONTINUE HANDLER FOR SQLEXCEPTION SET err=1;
  
  /*聲明當游標遍歷完全部記錄后將標志變量置成某個值*/
  DECLARE CONTINUE HANDLER FOR NOT FOUND
  SET done=1;
  
  /*開啟事務*/
  START TRANSACTION;
  
  /*打開游標*/
  OPEN cur;
  
  /*使用LOOP循環(huán)遍歷*/
  out_loop:LOOP
  
    /*將每一條結果對應的字段值賦值給變量*/
    FETCH cur INTO idval,taskIdval,groupIdval,emailval;
    IF done = 1 THEN
      LEAVE out_loop;
    END IF;
    
    /*打開第二個游標*/
    OPEN cur2;
      SET done = 0;
      FETCH cur2 INTO infoId;
      
      /*如果正式表不存在相同groupId and email記錄，添加到正式表*/
      IF done = 1 THEN
      
        /*插入正式表*/
        INSERT INTO `t_email_info` VALUES(idval,emailval,groupIdval,0,'',NOW(),'admin',NOW(),'admin');
        
        /*刪除臨時數(shù)據(jù)*/
        DELETE FROM `t_email_data_temp` WHERE id = idval;
        
        /*計數(shù)器，每1000條才提交*/
        SET counts = counts + 1;
        
        /*發(fā)生異常，回滾*/
        IF err=1 THEN
          SET isrollback=1;
          ROLLBACK;
        ELSE
          IF counts = 1000 THEN
            COMMIT;
            /*達到1000條提交后，重置計數(shù)器*/
            SET counts=0;
          END IF;
        END IF;
      ELSE
        /*已經(jīng)存在相同記錄，則刪除該記錄*/
        IF done=0 THEN
          DELETE FROM `t_email_data_temp` WHERE id = idval;
        END IF;
      END IF;
      FETCH cur2 INTO infoId;
    CLOSE cur2;
    
    /*控制外部的循環(huán)，該步驟不能缺少，否則只循環(huán)一次就結束了*/
    SET done=0;
    
  END LOOP out_loop;
  CLOSE cur;
  
  /*如果沒有發(fā)生過回滾事件，則更新task狀態(tài)*/
  /*如果回滾過，不更新task狀態(tài)，下次執(zhí)行任務的時候，會再次將剩余沒有提交的數(shù)據(jù)進行添加到正式表*/
  IF isrollback=0 THEN
    UPDATE `t_email_task` t SET t.`if_finish` = 1 WHERE t.`id`=jobId;
  END IF;
  
  END$$

DELIMITER ;