MySQL存儲過程中變量及循環的使用


1、用游標循環

BEGIN  

-- 定義變量 
   
    -- 定義done 
    DECLARE done INT;
    -- 定義 ammeter_id_bl
    DECLARE ammeter_id_bl  DOUBLE;
    -- 定義表名(tableName)游標
    DECLARE rs_ammeter_id CURSOR FOR  
    
-- 得到游標集合
    SELECT id FROM `res_meter` WHERE id<>1 AND id<>10 AND meter_type=1;    
        DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET done=1; 

-- 初始化done,為0,false
    SET done = 0;
-- 打開游標
    OPEN rs_ammeter_id; 
-- 遍歷游標(開始循環)
            REPEAT  
                    FETCH  rs_ammeter_id into ammeter_id_bl;
                    
                        IF done<>1 then
             /*
                            1、處理要插入的數據
                            */ 
             -- 給變量賦值
                        
                            SET @ammeter_id_bl=ammeter_id_bl;
              
                            SELECT t.* 
                            INTO 
                                     @min_meter_count_top
                                    ,@min_meter_count_max
                                    ,@min_meter_count_avg
                                    ,@min_meter_count_min
                                    ,@add_top
                                    ,@add_max
                                    ,@add_avg
                                    ,@add_min
                                    ,@collect_time
                                    ,@meter_status
                            FROM 
                            (
                                SELECT
                                     meter_count_top
                                    ,meter_count_max
                                    ,meter_count_avg
                                    ,meter_count_min
                                    ,ROUND(RAND()*10+4,2) add_top
                                    ,ROUND(RAND()*8+3,2) add_max
                                    ,ROUND(RAND()*7+2,2) add_avg
                                    ,ROUND(RAND()*6+1,2) add_min
                  ,DATE_ADD(collect_time, INTERVAL 30 MINUTE) collect_time
                  ,ROUND(RAND(),0) meter_status
                                FROM
                                    cap_ammeter_201810
                                WHERE
                                    collect_time = (
                                        SELECT
                                            MAX(collect_time) collect_time
                                        FROM
                                            cap_ammeter_201810
                                        WHERE
                                            ammeter_id = @ammeter_id_bl
                                        GROUP BY
                                            ammeter_id
                                    )
                                AND ammeter_id = @ammeter_id_bl
                            )t;
             
                        
              SET @meter_count_top=ROUND(@min_meter_count_top+@add_top,2)
                                 ,@meter_count_max=ROUND(@min_meter_count_max+@add_max,2)
                                 ,@meter_count_avg=ROUND(@min_meter_count_avg+@add_avg,2)
                                 ,@meter_count_min=ROUND(@min_meter_count_min+@add_min,2);

             SET @meter_count=ROUND(@meter_count_top+@meter_count_max+@meter_count_avg+@meter_count_min,2);
                            -- 查看變量的值
/*
                            SELECT
                                 @ammeter_id_bl  
                                ,@collect_time 
                                ,@meter_status 
                                ,@min_meter_count_top 
                                ,@min_meter_count_max 
                                ,@min_meter_count_avg 
                                ,@min_meter_count_min 
                                ,@add_top 
                                ,@add_max 
                                ,@add_avg 
                                ,@add_min 
                                ,@meter_count_top 
                                ,@meter_count_max 
                                ,@meter_count_avg 
                                ,@meter_count_min;
*/

                         /*
                            2、插入數據

                            */ 
              -- 1)寫sql語句 如果要用到變量,使用CONCAT()拼接
               -- 查詢出要插入的數據
             SET @queryDataSqlStr=CONCAT("SELECT 
                                 ",ROUND(@meter_count,2),"    meter_count
                                 ,'",@collect_time,"'   collect_time
                                 ,",@ammeter_id_bl,"   ammeter_id
                                 ,",@meter_status,"    meter_status 
                                 ,",ROUND(@meter_count_top,2)," meter_count_top
                                 ,",ROUND(@meter_count_max,2)," meter_count_max
                                 ,",ROUND(@meter_count_avg,2)," meter_count_avg
                                 ,",ROUND(@meter_count_min,2)," meter_count_min"
                                );
             -- 插入數據
             SET @insertSqlStr=CONCAT("INSERT INTO cap_ammeter_201810
                                      (
                                         meter_count
                                         ,collect_time
                                         ,ammeter_id
                                         ,meter_status
                                         ,meter_count_top
                                         ,meter_count_max
                                         ,meter_count_avg
                                         ,meter_count_min
                                       ) ",@queryDataSqlStr
                                     );
      
   
                         -- 4)查看sql語句
                         -- SELECT @insertSqlStr; 

                         -- 3)執行sql語句
                            PREPARE insertSqlStr FROM @insertSqlStr;
                            EXECUTE insertSqlStr;
      


                        END IF;
    -- 直到done變為true結束循環
                    UNTIL done END 
     REPEAT; 
    CLOSE rs_ammeter_id;  
END

2、while循環

BEGIN
    -- 定義變量
    DECLARE i INT DEFAULT 10;
    -- 開始循環
    WHILE i<13
    DO
        SET @day_bl=i;
        SET @createSqlStr=CONCAT("CREATE TABLE cap_ammeter_2017",@day_bl," 
                      ( `id`
bigint(20) NOT NULL AUTO_INCREMENT, `meter_count` double(14,2) DEFAULT NULL COMMENT '電表讀數', `collect_time` datetime DEFAULT NULL COMMENT '采集時間', `ammeter_id` bigint(20) NOT NULL COMMENT '電表id,對應res_meter的id', `meter_status` int(1) NOT NULL COMMENT '電表狀態 0:正常;1:異常', `meter_count_top` double(14,2) DEFAULT NULL COMMENT '尖值電量', `meter_count_max` double(14,2) DEFAULT NULL COMMENT '峰值電量', `meter_count_avg` double(14,2) DEFAULT NULL COMMENT '平值電量', `meter_count_min` double(14,2) DEFAULT NULL COMMENT '谷值電量', PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=19576 DEFAULT CHARSET=utf8;"); -- 查看sql -- SELECT @createSqlStr; -- 運行sql PREPARE createSqlStr FROM @createSqlStr; EXECUTE createSqlStr; SET i=i+1; END WHILE; COMMIT; END

 


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