基于来自另一个表的条件的SUM列

Question

I have two tables.

Table 1 is:

Week / Team  / Player  / Stat1 / Stat2 / Stat3 / ...<br>
   1 / Team1 / Player1 / #     / #     / #     / ...<br>
   1 / Team2 / Player2 / #     / #     / #     / ...

Table 2 is:

Player  / Team  / Played Game / Tiebreaker /
Player1 / Team1 / N           / #
Player2 / Team2 / Y           / #

Where Played Game either displays a Y means they have played at least one game and N means they haven't played any.

What I'm trying to do is sum the stats by column for each player from Table 1 and add their tiebreaker value from Table 2 to it, but I want a condition where if Played Game is equal to N, it just returns 0 as the value. Hopefully this makes sense.

This is my code:

$sql = "SELECT Player, 

SUM (Stat1) AS Stat1,
SUM (Stat2) AS Stat2,
SUM (Stat3) AS Stat3

FROM Table 1

GROUP BY Player
ORDER BY Stat1 DESC";

Which obviously just sums the values up for me. My problem is I'm not sure how to retrieve the information from the other table and do what I want in the same query. I've tried a CASE WHEN and IF statement with the sum, but hasn't worked. I'm new, so I'm trying to learn, but I'm currently stuck.

Any help is greatly appreciated.

Answer 1

You want conditional summation, which is using a CASE statement as the argument for an aggregation function:

SELECT t1.Player, 
       (SUM(CASE WHEN t2.Played = 'Y' THEN Stat1 ELSE 0 END) +
        MAX(CASE WHEN t2.Played = 'Y' THEN TIEBREAKER ELSE 0 END)
       ) AS Stat1,
       SUM(CASE WHEN t2.Played = 'Y' THEN Stat2 ELSE 0 END) AS Stat2,
       SUM(CASE WHEN t2.Played = 'Y' THEN Stat3 ELSE 0 END) AS Stat3
FROM Table1 t1 LEFT JOIN
     Table2 t2
     ON t1.player = t2.player AND t1.team = t2.team
GROUP BY t1.Player
ORDER BY Stat1 DESC;

Answer 2

To get data from both tables include the other table in

`FROM table1, table2` 

and join them with

`Where Table1.Player=Table2.Player`

That way, in the result the Player column will have every player once, the sum columns (as Stat1, Stat2, Stat3) will be summing the Stat column for each record in Table2 that has a corresponding Player in Table1 (which is all of them).

I don't know the php part, and I don't know what you mean by

I only want the tiebreaker added once, after the stats have been summed.

but I think this query will work right for the rest.

`SELECT Table2.Player, #I assume Table1.Player has repeat values and stuff,
SUM ( if ( Table2.PlayedGame="Y", Table1.Stat1, 0) ) AS Stat1,
SUM ( if ( Table2.PlayedGame="Y", Table1.Stat2, 0) ) AS Stat2,
SUM ( if ( Table2.PlayedGame="Y", Table1.Stat3, 0) ) AS Stat3
FROM Table1, Table2
Where Table1.Player = Table2.Player
GROUP BY Player
ORDER BY Stat1 DESC";`