mysql temporal year

Question

I'm having trouble with the modeling and implementing of "temporal" events in my championship db.

I have three entity: player, team, transfer, championship and I want to track the players' transfer during a championship ( a player can be transferred to another team during a championship)

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)

thanks.

Answer 1

You can try this query for example:

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

It should return all players with teams they played in, from PeriodFrom to PeriodTo.