我有以下代码，它通过服务器端API将一些数据添加到数据库中。字段order_number应通过$OrderNumberNext创建，该字段由count（*）+1作为order_num变量计算。
然而，完成此操作后检查数据库显示，这只会计算为0（零）。我应该为此使用不同的函数调用吗？
function addChartToSet($chartId, $setId){
$chartWithId = $this->db->get_var($this->db->prepare("select id from chords where chord_id=%s",$chartId));
$setWithId = $this->db->get_var($this->db->prepare("select id from sets where set_id=%s",$setId));
$orderNumberNext = $this->db->get_var($this->db->prepare("select count(*)+1 as `order_num` from `chords_inside_sets` where `set_id`=%s",$setId));
$this->db->query($this->db->prepare("update sets set `last_updated_time`=NOW() where `set_id`=%s",$setId));
$this->db->query($this->db->prepare("insert into `chords_inside_sets` set `chord_id`=%s , `set_id`=%s, `order_number`= %s",$chartWithId,$setWithId,$orderNumberNext));
return array("last_updated_time"=> $this->getMaxUpdatedTimeForSet($setId), "query"=> $this->db->last_query);
}
您在获取数据的查询中添加了1。它不能工作。首先通过SELECT查询获取计数，然后在下一行添加一个，如下所示：
$orderNumberNext = $this->db->get_var($this->db->prepare("select count(*) as `order_num` from `chords_inside_sets` where `set_id`=%s",$setId));
$orderNumberNext++;