如何使用 codeigniter 中的连接查询 table 中的 select 行？

Question

我有两个 table competition_registration 和 competition_schedule。我已经 select 从 competition_registration 查询 selecting 行。这是我的代码，如下所示：

$this->db->select('competition_registration.permenent_registration_number');
    $this->db->from('competition_registration');
    $where = "permenent_registration_number is  NOT NULL";
    $this->db->where($where);
    $this->db->join('competition_schedule', 'competition_schedule.competition_schedule_id = competition_registration.competition_schedule_id');
    $this->db->join('competition_schedule', 'competition_schedule.period_id = 6');
    $this->db->join('competition_schedule', 'competition_schedule.competition_level_id = 3');
    $query = $this->db->get();  echo $this->db->last_query();exit;

但这显示错误。任何人都可以检查此查询并为我纠正吗？

我想 select 两个 table 中具有相同 competition_schedule_id 和 competition_level_id 等于 3 和 period_id 等于 6 的列competition_schedule table .

Answer 1

希望对您有所帮助:

将 competition_schedule.period_id = 6 和这个 competition_schedule.competition_level_id = 3 放在 where 子句中，如下所示：

$this->db->select('competition_registration.permenent_registration_number');
$this->db->from('competition_registration');
$this->db->join('competition_schedule', 'competition_schedule.competition_schedule_id = competition_registration.competition_schedule_id');
$where = "competition_registration.permenent_registration_number is  NOT NULL";

$this->db->where($where);
$this->db->where('competition_schedule.period_id' , '6');
$this->db->where('competition_schedule.competition_level_id','3');

//$this->db->join('competition_schedule', 'competition_schedule.period_id = 6');
//$this->db->join('competition_schedule', 'competition_schedule.competition_level_id = 3');
$query = $this->db->get();  
echo $this->db->last_query();
exit;

更多：https://www.codeigniter.com/user_guide/database/query_builder.html

如何使用 codeigniter 中的连接查询 table 中的 select 行？

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