php – mysql关系慢

2023年11月8日 209次阅读 
<?php
$db = new mysqli(//editted out db credentials);

if($db->connect_errno > 0){
    die('Unable to connect to database [' . $db->connect_error . ']');
}
$sql = "SELECT m.ID, m.Title, GROUP_CONCAT(a.Title) AS Artist
FROM mp3s m
LEFT JOIN artist_relations ar ON ar.mp3ID = m.ID
LEFT JOIN artists a ON a.ID = ar.artistID
GROUP BY m.ID
ORDER BY ID
LIMIT 0,30;
";

if($result = $db->query($sql)){
echo "<table>";
while($row = $result->fetch_assoc()){
    echo "<tr>";  
    echo "<td>".$row['Title']."</td>";
    echo "<td>".$row['Artist']."</td>";
    echo "</tr>";  
}
echo "</table>";
}

?>

此查询工作正常,但速度非常慢.

该数据库有3个字段：

`artists` : ID , Title
`mp3s` : ID , Title
`artist_relations` : mp3ID , artistID

我需要这个：

row1: titlemusic1 - artist1 , artist4 , artist5
row2: titlemusic2 - artist1
row3: titlemusic1 - artist3 , artist8
row4: titlemusic1 - artist9 , artist10
...

mp3s,artist& artist_relations每个都有超过20000条记录

EXPLAIN SELECT m.ID, m.Title, .... :
    id  select_type     table   type    possible_keys   key     key_len     ref     rows    Extra   
    1   SIMPLE  m   ALL     NULL    NULL    NULL    NULL    23718   Using temporary; Using filesort
    1   SIMPLE  ar  ALL     NULL    NULL    NULL    NULL    24337   
    1   SIMPLE  a   eq_ref  PRIMARY     PRIMARY     4   ganools_rj.ar.artistID  1

–

– 表artist_relations的表结构

创建表如果不存在artist_relations(
  artistID int(11)NOT NULL,
  mp3ID int(11)NOT NULL
)ENGINE = InnoDB DEFAULT CHARSET = latin1;

–

– 表艺术家的表结构

创建表如果不是艺术家(
  ID int(11)NOT NULL AUTO_INCREMENT,
  标题varchar(155)NOT NULL
  主要钥匙(ID)
)ENGINE = InnoDB DEFAULT CHARSET = latin1 AUTO_INCREMENT = 9005;

–

– 表mp3的表结构

CREATE TABLE IF NOT NOT EXISTS mp3s(
  ID int(11)NOT NULL AUTO_INCREMENT,
  标题varchar(155)NOT NULL,
  imageURL varchar(155)NOT NULL,
  mp3URL varchar(155)NOT NULL,
  说明文字,
  抒情文字,
  album varchar(155)DEFAULT NULL,
  play int(11)DEFAULT NULL,
  pubDate日期NOT NULL,
  主要钥匙(ID)
)ENGINE = InnoDB DEFAULT CHARSET = latin1 AUTO_INCREMENT = 22936;

最佳答案 尝试为artist_relations.mp3ID,artist_relations.artistID和mp3s.ID创建索引.见
CREATE INDEX

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