mysql临时年

Question

我在锦标赛数据库中建立和实施“时间”事件时遇到了麻烦。

我有三个实体：球员，球队，转会，冠军，我想跟踪球员在冠军赛期间的转会（球员可以在冠军期间转移到另一支球队）

championship(id_championship*, name, year*)
player (id_player*, name, number, id_team*)
team (id_team, name)
transfer (id_player*, id_team_from*, id_team_to*, transfer _date)

感谢。

Answer 1

您可以尝试此查询，例如：

Select T1.id_player, T1.id_team_from as Team, T1.Transfer_date as PeriodFrom, 
T2.Transfer_date as PeriodTo
            from  
        (Select id_player,id_team_from, id_team_to, Transfer_date, 
        row_number() over (partition by id_player order by transfer_date desc) RN1)T1
            inner join 
        (Select id_player,id_team_from, id_team_to, Transfer_date, 
        row_number() over (partition by id_player order by transfer_date desc) RN2)T2
            on T1.RN1=T2.RN2+1
            and T1.id_player=T2.id_player

它应该让所有参与其中队伍的球员从PeriodFrom返回到PeriodTo。