在另一个表中最大日期之前和之后的一个表中计算记录。

(MySql engine) I have a table that records contacts between staff and members of a club called "Contacts". I need to know whether the latest contact made a positive effect on a members attendance by comparing the average number of times the member logged before and after that contact during an overall time period. Logins are stored in the logins table. User info is stored in the users table.(MySql engine) I have a table that records cont