MySQL存储过程中变量及循环的使用

1、用游标循环

BEGIN  

-- 定义变量 
   
    -- 定义done 
    DECLARE done INT;
    -- 定义 ammeter_id_bl
    DECLARE ammeter_id_bl  DOUBLE;
    -- 定义表名（tableName）游标
    DECLARE rs_ammeter_id CURSOR FOR  
    
-- 得到游标集合
    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，为0，false
    SET done = 0;
-- 打开游标
    OPEN rs_ammeter_id; 
-- 遍历游标（开始循环）
            REPEAT  
                    FETCH  rs_ammeter_id into ammeter_id_bl;
                    
                        IF done<>1 then
             /*
                            1、处理要插入的数据
                            */ 
             -- 给变量赋值
                        
                            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);
                            -- 查看变量的值
/*
                            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、插入数据

                            */ 
              -- 1）写sql语句 如果要用到变量，使用CONCAT()拼接
               -- 查询出要插入的数据
             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"
                 　　　　　　　　　　　　　　　);
             -- 插入数据
             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语句
                         -- SELECT @insertSqlStr; 

                         -- 3）执行sql语句
                            PREPARE insertSqlStr FROM @insertSqlStr;
                            EXECUTE insertSqlStr;
      


                        END IF;
    -- 直到done变为true结束循环
                    UNTIL done END 
     REPEAT; 
    CLOSE rs_ammeter_id;  
END

2、while循环

BEGIN
    -- 定义变量
    DECLARE i INT DEFAULT 10;
    -- 开始循环
    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 '电表读数',
                                     `collect_time` datetime DEFAULT NULL COMMENT '采集时间',
                                     `ammeter_id` bigint(20) NOT NULL COMMENT '电表id，对应res_meter的id',
                                     `meter_status` int(1) NOT NULL COMMENT '电表状态 0：正常；1：异常',
                                     `meter_count_top` double(14,2) DEFAULT NULL COMMENT '尖值电量',
                                     `meter_count_max` double(14,2) DEFAULT NULL COMMENT '峰值电量',
                                     `meter_count_avg` double(14,2) DEFAULT NULL COMMENT '平值电量',
                                     `meter_count_min` double(14,2) DEFAULT NULL COMMENT '谷值电量',
                                      PRIMARY KEY (`id`)
                                 ) ENGINE=InnoDB AUTO_INCREMENT=19576 DEFAULT CHARSET=utf8;");
            -- 查看sql
              -- SELECT @createSqlStr;
              -- 运行sql
        PREPARE createSqlStr FROM @createSqlStr;
              EXECUTE createSqlStr;



        SET i=i+1;


    END WHILE;
    COMMIT;
END