php - CodeIgniter：使用 WHERE 查询返回错误 :: $query = $this->db->query()

Question

我需要guest_id从new_guest列guest_nic_pp_dl等于变量guest_nic_pp_dl和LIMIT1 个结果的表中获取。然而，我写的代码以一个愚蠢的语法错误结束。如何使用变量值定义 WHERE 以匹配行？

解析错误：语法错误，第 20 行 C:\xampp\htdocs\bit\application\models\reservations_model.php 中的意外 '$guest_nic_pp_dl' (T_VARIABLE)

$query = $this->db->query('SELECT guest_id FROM new_guest WHERE guest_nic_pp_dl, '$guest_nic_pp_dl' LIMIT 1'); // Line 20
foreach ($query->result() as $row) {
    return $row->guest_id;

Answer 1

像这样试试

     $query = $this->db->query("SELECT guest_id FROM new_guest WHERE guest_nic_pp_dl, '$guest_nic_pp_dl' LIMIT 1"); 

Answer 2

$this->db->select('guest_id');

$this->db->where('guest_nic_pp_dl', $guest_nic_pp_dl);

$this->db->limit(1);

$query = $this->db->get('new_guest');

Answer 3

$query = $this->db->query('SELECT guest_id FROM new_guest WHERE guest_nic_pp_dl='.$guest_nic_pp_dl.' LIMIT 1');
foreach ($query->result() as $row) {
return $row->guest_id;
}