php - MySQL/PHP 计数

Question

我有 2 个 MySQL 表，一个用于存储专辑，另一个用于存储歌曲。我在表格中显示专辑列表，并且希望能够添加一个名为 songs 的列来显示该专辑中的歌曲数量。我现在的方式只会弄乱我的 table :

感谢大家的帮助!

Answer 1

假设“播放列表”是您认为的专辑，并且第一个 while 循环在播放列表上迭代，我会像这样重写您的代码:

while($row = mysql_fetch_array($rs)) {
    echo "<tr>\n";
    echo "<td>".$row['playlist_id']."</td>";

    // Assuming playlist_id is an integer value in your database
    $query = "
        SELECT Playlist_id, COUNT(Playlist_id) AS songCount
        FROM ws_music 
        WHERE Playlist_id = ". intval ($row['playlist_id']) ."
        GROUP BY Playlist_id 
    ";
    $result = mysql_query($query) or die(mysql_error());
    // No need for the second while loop
    $row2 = mysql_fetch_array($result);
    echo "<td>There are ". $row2['songCount'] ." ". $row2['Playlist_id'] ." song.</td>";
    echo "</tr>";
}