Mysql存储过程

Question

您好，我正在尝试在存储过程中运行一个循环，在其中，我根据date(curr_date)从select查询中获得值的总和。我需要在select query(curr_date)中循环date列。我面临的问题是，当我运行while循环时，它只从数据库中获取日期的第一个条目。

我的Mysql存储过程如下：

CREATE PROCEDURE `paf_calculation`(out avg_sum1 float(15,3))
BEGIN
    DECLARE day_count int;
    DECLARE extra_days int;
    DECLARE lookup_weeks int;
    DECLARE week_days INT;
    DECLARE count decimal;
    DECLARE datapoints int;
    DECLARE start_date date;
    DECLARE previous_days date; 
    DECLARE sum_extra_days float(15,3);
    DECLARE roid int;
    DECLARE historylookup_weeks int;    
    DECLARE avg_sum float;
    DECLARE i int;
    DECLARE curr_date date;

    set i = 0;
    SET WEEK_DAYS = 7;

    Set count = 0.5;



    select datediff('2016-10-10','2016-10-7') into historylookup_weeks;


    /** counts the number of days from the current week start and end days */
    select datediff('2016-10-10','2016-10-7') into day_count;

    /**No of extra days if the current week is more or less than 7 */
    SET extra_days = day_count - WEEK_DAYS;

    /**calculates the date 56 days from the current start week date */
    select date_sub('2016-10-17',interval 56 day) into previous_days ;

    /**calculates the datapoints*/ 
    set avg_sum1=0;

    Set datapoints = day_count * lookup_weeks; 
    set i = 0;

    set curr_date = '2016-10-08'; 


    while curr_date < '2016-10-17' do
    SELECT SUM(actual_volume) into avg_sum FROM volume_trackers WHERE (date_inserted between '2016-08-23' AND '2016-10-17') AND (day_of_week in (dayofweek(curr_date))) and (ro_id=13);
    set curr_date=date_add(curr_date,interval 1 day);
    set avg_sum1=avg_sum+avg_sum1;
    END WHILE;  

END

Answer 1

您的查询看起来确实像编码一样循环，但我会修改sum_avg1计算，以允许将空值返回到平均和

set avg_sum1=coalesce(avg_sum,0) + avg_sum1;