MYSQL - 如何使用 SELECT 作为我的 WHERE

Question

我有两个表recordings，recording_metas我想选择一些元数据并使用这些元数据中的外键来查找相应的记录。这就是我到目前为止所拥有的。$recording_sql输出这个SELECT recording FROM recordings     INNER JOIN recording_metas     ON recordings.id = recording_metas.recording_id    WHERE recording_metas.recording_id IN (SELECT recording_id, meta_key, meta_value FROM recording_metas WHERE meta_key=? AND meta_value=?) LIMIT ?但是为什么我会收到以下错误？Fatal error:  Uncaught Error: Call to a member function bind_param() on bool在这一行$stmt->bind_param(str_repeat('s', count($mixed)), ...$mixed);，我确信它$meta_sql可以工作，因为我也用 LIMIT 指针单独测试了它，所以如果我使用它们，指针工作正常$meta_sqlPHPfunction retrieveRecordingsByMetaData($connection, $config, $metas, $limit){    $where = "";    for ($i = 0; $i < count($metas); $i++) {        $where .= "meta_key=? AND meta_value=? AND ";    }    $where = preg_replace('/ AND $/', '', $where);    $meta_sql = "SELECT recording_id, meta_key, meta_value FROM $config->meta_table WHERE $where";    $recording_sql = "SELECT recording FROM $config->recording_table     INNER JOIN $config->meta_table     ON $config->recording_table.id = $config->meta_table.recording_id    WHERE $config->meta_table.recording_id IN ($meta_sql) LIMIT ?";    echo ($recording_sql);    $stmt = $connection->prepare($recording_sql);    $mixed = associativeToArrayMixed($metas);    array_push($mixed, $limit);    $stmt->bind_param(str_repeat('s', count($mixed)), ...$mixed);    if (!$stmt->execute()) {        echo "Execute failed: (" . $stmt->errno . ") " . $stmt->error . " \r\n";        die();    }    $result = $stmt->get_result();    if ($result->num_rows > 0) {        while ($row = $result->fetch_assoc()) {            echo "recording found";        }    } else {        echo "0 results \r\n";    }}

Answer 1

您必须在 where 子句中只选择一列

WHERE recording_metas.recording_id IN 
  (SELECT recording_id FROM recording_metas WHERE meta_key=? AND meta_value=?) LIMIT ?

如果您想选择多于一列，则必须使用此处所示的元组 https://stackoverflow.com/a/44706402/5193536