[英]CodeIgniter - Active Record join
I got some code in my CodeIgniter model: 我在CodeIgniter模型中得到了一些代码:
$this->db->where('building_active', 1);
$this->db->select('*');
$this->db->from('buildings');
$this->db->join('users_buildings', 'users_buildings.building_id = buildings.building_id');
$this->db->join('buildings_levels', 'buildings_levels.level_id = users_buildings.level_id');
$buildings = $this->db->get()->result();
What I want to do: 我想做的事:
I want to select all buildings and join users_buildings if possible. 我想选择所有建筑物,并在可能的情况下加入users_buildings。 The current problem is, that only the buildings with a corresponding entry in users_buildings get selected. 当前的问题是,只有在users_buildings中具有相应条目的建筑物才被选中。
Since there would be no level_id for the second join clause then(if there are no users_buildings available for that building), there would have to be a fallback to change the join clause to buildings_levels.level_id = 0 由于第二个join子句将没有level_id(如果该建筑物没有users_buildings可用),则必须进行后备操作才能将join子句更改为buildings_levels.level_id = 0
I hope it's clear what I mean. 我希望我的意思很清楚。 I don't know if that's even possible. 我不知道那是否有可能。
Your first question is answered by changing your inner joins into left joins: 通过将内部联接更改为左联接可以回答第一个问题:
$this->db->join('users_buildings', 'users_buildings.building_id = buildings.building_id', 'left');
$this->db->join('buildings_levels', 'buildings_levels.level_id = users_buildings.level_id', 'left');
That will return null
for the missing values. 对于缺少的值,它将返回null
。 I don't quite get if you want that null to be a 0
, null
or something else. 如果您希望将该null设置为0
, null
或其他值,我不太了解。
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