MySql-循环浏览每个月的日期

Question

我有2张桌子。一个是工作（主）表，另一个是分配（交易）表。对于每项工作，我需要打印一个月中每天的分配数量。

我需要以以下格式打印分配数量。

我在存储过程中使用while循环尝试了此操作。但这没有帮助。

BEGIN

SET @start_day = DATE('2018-11-01');
SET @end_day = DATE_ADD(@start_day, INTERVAL 30 DAY);

SELECT 
job_id into @job_id
FROM 
jobs
WHERE
job_post_date BETWEEN @start_day AND @end_day;

WHILE(@start_day < @end_day) DO
 SELECT COUNT(allocation_id) FROM allocations WHERE allocations_job_id = 
@job_id AND allocations_assigned_date = @start_day;
 SET @start_day = DATE_ADD(@start_day, INTERVAL 1 DAY);
END WHILE;

END

Answer 1

如果您可以通过循环讨论所讨论月份的所有天数来创建动态sql，则应该可以解决您的问题。 动态sql应该看起来像

select j.job_name,
       sum(case when a.allocations_assigned_date = '2019-01-01' 
                then 1 else 0 end) as "1-JAN-2019",
       sum(case when a.allocations_assigned_date = '2019-01-02' 
                then 1 else 0 end) as "2-JAN-2019",
       sum(case when a.allocations_assigned_date = '2019-01-31' 
                then 1 else 0 end) as "31-JAN-2019"
  from jobs j inner join allocations a 
    on j.job_id = a.allocations_job_id
 group by j.job_name