How to count the retention rate in mysql

In this issue, the editor will bring you about how to count the retention rate in mysql. The article is rich in content and analyzed and described from a professional point of view. I hope you can get something after reading this article.

Sql code

Begin

Declare i int

Declare numareaId int (10)

Declare currentareaId int (10)

SELECT COUNT (areaId), MIN (areaId) INTO @ a

SET numareaId=@a

SET currentareaId=@b

Loop1:WHILE numareaId > 0 DO

SET @ AID = currentareaId

SET iTunes 1

While i=date_sub (curdate (), interval i day) and createTime=date_add (date_sub (curdate (), interval i day), interval 1 day) and loginTime=date_sub (curdate (), interval i day) and createTime=date_add (date_sub (curdate (), interval i day), interval 2 day) and loginTime=date_sub (curdate (), interval i day) and createTime=date_add (date_sub (curdate (), interval i day), interval 3 day) and loginTime=date_sub (curdate () Interval i day) and createTime=date_add (date_sub (curdate (), interval i day), interval 4 day) and loginTime=date_sub (curdate (), interval i day) and createTime=date_add (date_sub (curdate (), interval i day), interval 5 day) and loginTime=date_sub (curdate (), interval i day) and createTime=date_add (date_sub (curdate (), interval i day), interval 6 day) and loginTime=date_sub (curdate (), interval i day) and createTime=date_add (date_sub (curdate (), interval i day) Interval 7 day) and loginTime=date_sub (curdate (), interval i day) and createTime