Question

我的查询加载时间有很大问题。在这种情况下，我需要 hg_ft_won （表格：值）列中的值 home_team_id 和 away_team_id （表格：匹配）。

它确实有效。加载只需要很长时间。有没有人有想法如何通过提供替代查询来改善它？

$sql = $conn->query("SELECT m.home_team_name, 
       m.away_team_name, 
       m.home_team_id, 
       m.away_team_id, 
       m.starting_time, 
       m.starting_date, 
       m.match_id, 
       m.season_id, 
       m.competition_id, 
       s.season_name, 
       s.country_name, 
       s.competition_name, 

  (SELECT hg_ft_won 
   FROM `values` v 
   WHERE m.home_team_id = v.team_id 
     AND m.season_id = v.season_id ) AS hg_ft_won1, 

  (SELECT hg_ft_won 
   FROM `values` v 
   WHERE m.away_team_id = v.team_id 
     AND m.season_id = v.season_id ) AS hg_ft_won2, 

FROM matches m, 
     seasons s
WHERE m.season_id = s.id 
AND m.starting_date = '2017-02-11'");

值表

匹配表

来自webpagetest.org的

结果

Answer 1

从不在FROM子句中使用逗号。始终使用正确的，明确的JOIN语法。这基本上是您的查询：

SELECT . . .
       (SELECT hg_ft_won 
        FROM `values` v 
        WHERE m.home_team_id = v.team_id AND m.season_id = v.season_id
      ) AS hg_ft_won1, 
      (SELECT hg_ft_won 
       FROM `values` v 
       WHERE m.away_team_id = v.team_id AND
             m.season_id = v.season_id
      ) AS hg_ft_won2,
FROM matches m JOIN 
     seasons s
     ON m.season_id = s.id LEFT JOIN
     competition
     ON competition.id = ?.competition_id 
WHERE m.starting_date = '2017-02-11'");

对于此查询，您需要索引：

matches(starting_date, season_id)
seasons(id)（可能已经存在）
competition(id)（可能已经存在）
values(team_id, season_id, hg_ft_won)

我不知道competition_id的位置。它应该在最后一个键上添加到它所属的表中。

Answer 2

尝试此查询。尽可能创建所需的索引。


    SELECT m.home_team_name, 
        m.away_team_name, 
        m.home_team_id, 
        m.away_team_id, 
        m.starting_time, 
        m.starting_date, 
        m.match_id, 
        m.season_id, 
        m.competition_id, 
        s.season_name, 
        s.country_name, 
        s.competition_name, 
        v1.hg_ft_won  AS hg_ft_won1, 
        v2.hg_ft_won  AS hg_ft_won2, 
    FROM matches m 
        INNER JOIN seasons s ON m.season_id = s.id
        LEFT JOIN `values` v1 ON m.home_team_id = v1.team_id  AND m.season_id = v1.season_id
        LEFT JOIN `values` v2 ON m.home_team_id = v2.team_id  AND m.season_id = v2.season_id
    AND m.starting_date = '2017-02-11'

从另一个表中选择值 - 太慢

2 个答案: