0

次のクエリがあります。

SELECT
    A.player, A.score, B.kills, C.deaths, D.killed AS most_killed, D.kills AS most_killed_count, E.player AS most_killed_by, E.kills AS most_killed_by_count
FROM
(SELECT player, score FROM pvpr_scores WHERE player = 'Neutronix' AND milestone = 'default') AS A
LEFT JOIN (SELECT player, COUNT(*) AS kills FROM pvpr_kills WHERE player = 'Neutronix' AND milestone = 'default') AS B ON B.player= A.player
LEFT JOIN (SELECT killed, COUNT(*) AS deaths FROM pvpr_kills WHERE killed = 'Neutronix' AND milestone = 'default') AS C ON C.killed= A.player
LEFT JOIN (SELECT player, killed, COUNT(*) AS kills FROM pvpr_kills WHERE player = 'Neutronix' GROUP BY killed ORDER BY kills DESC LIMIT 1) AS D ON D.player= A.player
LEFT JOIN (SELECT player, killed, COUNT(*) AS kills FROM pvpr_kills WHERE killed = 'Neutronix' GROUP BY player ORDER BY kills DESC LIMIT 1) AS E ON E.killed= A.player

ただし、これらのサブクエリのいずれかが null を返すと、クエリ全体が失敗します。返された結果セット (1 行) でこれらの列を null にする代わりに、null クエリを使用したいと思います。

Neutronixのようにデータベースにないものに変更するdfdsjfと、エラーが発生します。

編集：これが私が行った修正です。

SELECT
    A.player, A.score, B.kills, C.deaths, D.killed AS most_killed, D.kills AS most_killed_count, E.player AS most_killed_by, E.kills AS most_killed_by_count
FROM
(SELECT player, score FROM pvpr_scores WHERE player = 'Gutterknife' AND milestone = 'default') AS A
LEFT OUTER JOIN (SELECT COUNT(*) AS kills FROM pvpr_kills WHERE player = 'Gutterknife' AND milestone = 'default') AS B ON TRUE
LEFT OUTER JOIN (SELECT COUNT(*) AS deaths FROM pvpr_kills WHERE killed = 'Gutterknife' AND milestone = 'default') AS C ON TRUE
LEFT OUTER JOIN (SELECT killed, COUNT(*) AS kills FROM pvpr_kills WHERE player = 'Gutterknife' GROUP BY killed ORDER BY kills DESC LIMIT 1) AS D ON TRUE
LEFT OUTER JOIN (SELECT player, COUNT(*) AS kills FROM pvpr_kills WHERE killed = 'Gutterknife' GROUP BY player ORDER BY kills DESC LIMIT 1) AS E ON TRUE
4

2 に答える 2

1

問題はサブクエリではないと思います。問題はドライバークエリだと思います：

FROM (SELECT player, score
      FROM pvpr_scores
      WHERE player = 'Neutronix' AND milestone = 'default'
     ) AS A . . .

このクエリに一致するものがない場合、他のクエリには一致する行がありません。

これを修正する方法がよくわかりません。次のようなことができると思います：

FROM (select 'Neutronix' as player) t left outer join
     (SELECT player, score
      FROM pvpr_scores
      WHERE player = 'Neutronix' AND milestone = 'default'
     ) AS A
     on t.player = a.player left outer join . . .

そして、節joinの残りの条件を の代わりに に変更します。fromt.a.

于 2013-07-20T02:10:28.493 に答える
0

FROM でサブ セレクトを実行するのはなぜですか。単純な FROM スコアだけでもかまいません。

'ON' 句に複数の条件を指定することもできます。たとえば、ON b.player = a.player および b.milestone = a.milestone です。

サブ選択ではなく、SUM と IF を組み合わせて結果を得ることができます。

明らかにこれはテストされていませんが、次の行に沿ってクエリにアプローチします。

SELECT scores.player,
        scores.score,
        sum(if(kills.player is not null, 1, 0) as kills,
        sum(if(deaths.player is not null, 1, 0) as deaths
        killed.kills as most_killed,
        killed.killed as most_killed_count,
        killed_by.kills as most_killed_by_count,
        killed_by.killed as most_killed_by
FROM pvpr_scores as scores
LEFT JOIN pvpr_kills as kills
    on kills.player = player
    and kills.milestone = scores.milestone
LEFT JOIN pvpr_deaths as deaths
    on deaths.player = player
    and deaths.milestone = scores.milestone
LEFT JOIN (SELECT killed, player, count(killed) as kills
            FROM kills
            GROUP BY killed, player
            HAVING MAX( count(killed) ) ) as killed
    ON killed.player = scores.player
LEFT JOIN (SELECT killed, player, count(player) as kills
            FROM kills
            GROUP BY player, killed
            HAVING MAX( count(player) ) ) as killed_by
    ON killed_by.killed = scores.player

WHERE scores.player = 'neutronix'
  AND scores.milestone = 'default'

   GROUP BY scores.player
于 2013-07-20T02:45:56.977 に答える