我正在尝试修改wordpress插件，使其更适合我们的需要。我有一个自定义的user\\u meta，名为practice，我们根据实践来分隔用户，因此我们还需要根据实践来分隔测验结果。我的问题是，我无法让我的查询返回实践。有人能看看这个告诉我我做错了什么吗？

    function save_score( $json, $user_id = null, $practice = null )
    {
        global $wpdb, $data;
        $db_name = $wpdb->prefix . \'plugin_slickquiz_scores\';


        $data    = json_decode( stripcslashes( $json ) );
        $set     = array();
        $now     = date( \'Y-m-d H:i:s\' );
        $user_id = $user_id ? $user_id : get_current_user_id();
        $practiceKey = \'user_practice\';
       // $practice = $wpdb->get_results( "SELECT meta_value FROM $usrmeta WHERE user_id = $user_id AND meta_key = \'user_practice\'" );
       // $usrlevel = $usrlevel ? $usrlevel : $wpdb->get_var( "SELECT meta_value FROM $usrmeta WHERE user_id = \'".$user_id."\' AND meta_key = user_practice_level" );

        $userMeta = $wpdb->prefix . `usermeta`;
        $sql = $wpdb->prepare( "SELECT meta_value FROM %s WHERE user_id = %d AND meta_key = %d",$userMeta,$user_id,$practiceKey );
        $practice = $wpdb->get_var( $sql );

        $set[\'name\']        = $data->name;
        $set[\'score\']       = $data->score;
        $set[\'quiz_id\']     = $data->quiz_id;
        //$set[\'createdBy\']   = $user_id;
        //$set[\'createdDate\'] = $now;
        $set[\'usr\']         = $user_id;
        $set[\'usr_practice\'] = $practice;




        $wpdb->insert( $db_name, $set );
    }

}
}

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