我认为自己是mysql / php的初学者，当你看到我的代码时不要感到震惊：D。我用mysql查询创建了一个php函数，这个函数在调用函数时需要很长时间（大部分时间）。他们很少会被快速执行。在PHPmyadmin中，这个php函数中的单个查询运行速度快且没有错误。
public function getAllMusicDataNew($playlist_name, $mysqli) {
// einzeln alle titel / alle künstler / alle alben auflisten als array
$sql1 = "Select distinct title, artist, album from songs where id not in(Select distinct id from songs where id
IN(Select id from songs where title IN(Select title from songs where id
IN(Select song_id from playlist where playlist_id IN (Select playlist_id from playlists where name = '$playlist_name')))))";
$getTitles = $mysqli->query($sql1);
$sql2 = "Select distinct artist from songs where id not in(Select distinct id from songs where id IN
(Select id from songs where artist IN(Select artist from songs where id IN(Select song_id from playlist
where playlist_id IN (Select playlist_id from playlists where name = '$playlist_name')))))";
$getArtists = $mysqli->query($sql2);
$sql3 = "Select distinct album, artist from songs where id not in( Select distinct id from songs where id IN(Select id from songs where album IN( Select album from songs where id IN( Select song_id from playlist
where playlist_id IN ( Select playlist_id from playlists where name = '$playlist_name'))and album <> '')))";
$getAlbums = $mysqli->query($sql3);
$sql4 = "Select distinct title, artist, album from songs where id in(Select distinct id from songs where id
IN(Select id from songs where title IN(Select title from songs where id
IN(Select song_id from playlist where playlist_id IN (Select playlist_id from playlists where name = '$playlist_name')))))";
$getTitles_added = $mysqli->query($sql4);
$sql5 = "Select distinct artist from songs where id in(Select distinct id from songs where id IN
(Select id from songs where artist IN(Select artist from songs where id IN(Select song_id from playlist
where playlist_id IN (Select playlist_id from playlists where name = '$playlist_name')))))";
$getArtists_added = $mysqli->query($sql5);
$sql6 = "Select distinct album, artist from songs where id in( Select distinct id from songs where id IN(Select id from songs where album IN( Select album from songs where id IN( Select song_id from playlist
where playlist_id IN ( Select playlist_id from playlists where name = '$playlist_name'))and album <> '')))";
$getAlbums_added = $mysqli->query($sql6);
while ($row = $getTitles->fetch_assoc()) {
$results_array1[] = $row;
}
while ($row = $getArtists->fetch_assoc()) {
$results_array2[] = $row;
}
while ($row = $getAlbums->fetch_assoc()) {
$results_array3[] = $row;
}
if(mysqli_num_rows($getTitles_added)!=0) {
while ($row = $getTitles_added->fetch_assoc()) {
$results_array4[] = $row;
}
while ($row = $getArtists_added->fetch_assoc()) {
$results_array5[] = $row;
}
while ($row = $getAlbums_added->fetch_assoc()) {
$results_array6[] = $row;
}
} else {
$results_array4[] = "empty";
$results_array5[] = "empty";
$results_array6[] = "empty";
}
// print_r($titles);
$titles["titles"] = $results_array1;
$artists["artists"] = $results_array2;
$albums["albums"] = $results_array3;
$titles_added["titles_added"] = $results_array4;
$artists_added["artists_added"] = $results_array5;
$albums_added["albums_added"] = $results_array6;
// printf($array_merge($results_array1, $results_array2, $results_array3));
return array_merge($titles, $artists, $albums, $titles_added, $artists_added, $albums_added);
}
-- phpMyAdmin SQL Dump
-- version 4.2.12deb2+deb8u1
-- http://www.phpmyadmin.net
--
-- Host: localhost
-- Erstellungszeit: 10. Aug 2016 um 17:04
-- Server Version: 5.5.44-0+deb8u1
-- PHP-Version: 5.6.23-0+deb8u1
SET SQL_MODE = "NO_AUTO_VALUE_ON_ZERO";
SET time_zone = "+00:00";
/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;
/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;
/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;
/*!40101 SET NAMES utf8 */;
--
-- Datenbank: `musicbox2`
--
-- --------------------------------------------------------
--
-- Tabellenstruktur für Tabelle `playlist`
--
CREATE TABLE IF NOT EXISTS `playlist` (
`playlist_id` int(11) NOT NULL,
`track_id` int(11) NOT NULL,
`song_id` int(11) NOT NULL,
`votes` int(11) NOT NULL
) ENGINE=InnoDB AUTO_INCREMENT=1189 DEFAULT CHARSET=latin1;
-- --------------------------------------------------------
--
-- Tabellenstruktur für Tabelle `playlists`
--
CREATE TABLE IF NOT EXISTS `playlists` (
`playlist_id` int(11) NOT NULL,
`name` varchar(60) NOT NULL,
`created_at` datetime NOT NULL,
`updated_at` datetime NOT NULL
) ENGINE=InnoDB AUTO_INCREMENT=13 DEFAULT CHARSET=latin1;
-- --------------------------------------------------------
--
-- Tabellenstruktur für Tabelle `songs`
--
CREATE TABLE IF NOT EXISTS `songs` (
`id` int(11) NOT NULL,
`path` varchar(100) NOT NULL,
`artist` varchar(60) NOT NULL,
`title` varchar(60) NOT NULL,
`album` varchar(50) NOT NULL,
`added_at` datetime NOT NULL
) ENGINE=InnoDB AUTO_INCREMENT=4803 DEFAULT CHARSET=latin1;
-- --------------------------------------------------------
--
-- Tabellenstruktur für Tabelle `users`
--
CREATE TABLE IF NOT EXISTS `users` (
`userID` int(11) NOT NULL,
`voices` int(11) NOT NULL,
`pass` varchar(18) NOT NULL,
`created_at` datetime NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
--
-- Indizes der exportierten Tabellen
--
--
-- Indizes für die Tabelle `playlist`
--
ALTER TABLE `playlist`
ADD PRIMARY KEY (`track_id`), ADD KEY `song_id` (`song_id`), ADD KEY `playlist_id` (`playlist_id`);
--
-- Indizes für die Tabelle `playlists`
--
ALTER TABLE `playlists`
ADD PRIMARY KEY (`playlist_id`);
--
-- Indizes für die Tabelle `songs`
--
ALTER TABLE `songs`
ADD PRIMARY KEY (`id`), ADD UNIQUE KEY `title` (`title`,`artist`,`album`);
--
-- Indizes für die Tabelle `users`
--
ALTER TABLE `users`
ADD PRIMARY KEY (`userID`);
--
-- AUTO_INCREMENT für exportierte Tabellen
--
--
-- AUTO_INCREMENT für Tabelle `playlist`
--
ALTER TABLE `playlist`
MODIFY `track_id` int(11) NOT NULL AUTO_INCREMENT,AUTO_INCREMENT=1189;
--
-- AUTO_INCREMENT für Tabelle `playlists`
--
ALTER TABLE `playlists`
MODIFY `playlist_id` int(11) NOT NULL AUTO_INCREMENT,AUTO_INCREMENT=13;
--
-- AUTO_INCREMENT für Tabelle `songs`
--
ALTER TABLE `songs`
MODIFY `id` int(11) NOT NULL AUTO_INCREMENT,AUTO_INCREMENT=4803;
--
-- AUTO_INCREMENT für Tabelle `users`
--
ALTER TABLE `users`
MODIFY `userID` int(11) NOT NULL AUTO_INCREMENT;
--
-- Constraints der exportierten Tabellen
--
--
-- Constraints der Tabelle `playlist`
--
ALTER TABLE `playlist`
ADD CONSTRAINT `playlist_ibfk_1` FOREIGN KEY (`song_id`) REFERENCES `songs` (`id`) ON DELETE CASCADE,
ADD CONSTRAINT `playlist_ibfk_2` FOREIGN KEY (`playlist_id`) REFERENCES `playlists` (`playlist_id`) ON DELETE CASCADE;
/*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */;
/*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */;
/*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;
答案 0 :(得分：0)
使用像这样的连接查询我有相同的结果和它的工作:)仍然不知道为什么嵌套查询需要40-50秒。 感谢用户Dibakar Paul帮帮我！
$sql1 = "Select distinct title, artist, album
from songs where id not in(Select distinct song.id
from songs song inner join playlist playlist
on playlist.song_id=song.id
inner join playlists playlists
on playlists.playlist_id=playlist.playlist_id
and playlists.name = '$playlist_name')";
$sql2 = "Select distinct song.title, song.artist, song.album
from songs song inner join playlist playlist
on playlist.song_id=song.id
inner join playlists playlists
on playlists.playlist_id=playlist.playlist_id
and playlists.name = '$playlist_name'";