我编写了以下代码，试图获取数据库中3个表中的条目数量。当我在phpMyAdmin中使用查询时，查询可以工作，但当我运行此代码时，我得到：
Error creating SQL statement
它是由CCD_ 2语句生成的，我不知道它为什么不起作用。提前感谢：）
<?php
include 'connection.php';
$countArtists = $countAlbums = $countTracks = 0;
/* Create queries to get counts from each table */
$sql = "SELECT COUNT(*) FROM artist;";
$sql .= "SELECT COUNT(*) FROM cd;";
$sql .= "SELECT COUNT(*) FROM tracks;";
$stmt = $conn->prepare($sql);
if(!$stmt)
{
echo "Error creating SQL statement";
return 1;
}
$stmt->execute();
$stmt->bind_result($countArtists, $countAlbums, $countTracks);
echo "<li>Number of Artists: $countArtists</li><br>'n" .
"<li>Number of Albums: $countAlbums</li><br>'n" .
"<li>Number of Tracks: $countTracks</li><br>'n";
?>
我想你想要一个这样的单一查询：
$sql = "SELECT (SELECT COUNT(*) FROM artist) as countArtists, ".
"(SELECT COUNT(*) FROM cd) as countAlbums, ".
"(SELECT COUNT(*) FROM tracks) as countTracks";
这是一个有三列的查询，而不是三个单独的查询。