Question

Hi everyone I have a problem with a SQL query and I can not find a solution.

In my database I have two tables, Mytable1 and Mytable2. Mytable1 contains columns idCalendar, idPlayer, datePlaying and Mytable2 contains columns idPlayer and namePlayer.

I want to extract foreach date in Mytable1 the names of players who did not play.

For example
Mytable1 (contains player and playing date):


idCalendar|idPlayer|datePlaying

1         |     1  | 05/01/2012
2         |     2  | 06/01/2012
3         |     3  | 08/01/2012
4         |     2  | 05/01/2012

Mytable2 (contains all player names) :


idPlayer|namePlayer

1  | P1
2  | P2
3  | P3
4  | P4

I’d like to create a view that displays the following result :

ViewResult (players who haven’t played by date):


datePlaying | playerName

05/01/2012  | P2
05/01/2012  | P3
06/01/2012  | P1
06/01/2012  | P3
08/01/2012  | P1
08/01/2012  | P2

As you can see I need result with this information:
– in 05/01/2012 P2 and P3 haven’t played.
– in 06/01/2012 P1 and P3 haven’t played.
– in 08/01/2012 P1 and P2 haven’t played.

I hope I have been clear enough. Thank you in advance.

Answer 1

Probably something as simple as this would work.

select
    d.datePlaying, p.namePlayer
from
    table2 p
cross join 
    (select distinct datePlaying from table1) d
left join
    table1 t on t.idPlayer = p.idPlayer and t.datePlaying = d.datePlaying
where
    t.idPlayer is null

As a side note what happens if you have a date where non of the players played? You wouldnt have an entry in table2. Do you care or should there be a 3rd table to represent dates that any of the players should have played. This dates table would be used to replace my alias ‘d’ cross-joined table.