问题描述
我有以下 php-codeigniter 脚本，它尝试使用活动记录语法增加记录的字段:
I have the following php-codeigniter script which attempts to increment a field of a record using active-record syntax:
$data = array('votes' => '(votes + 1)');
$this->db->where('id', $post['identifier']);
$this->db->update('users', $data);
这会产生以下 SQL:
This produces the following SQL:
"UPDATEusersSETvotes='(votes + 1)' WHEREid='44'"
"UPDATEusersSETvotes= '(votes + 1)' WHEREid= '44'"
它没有运行，但是这个 SQL 可以做我正在寻找的东西:"UPDATEusersSETvotes= (votes + 1) WHEREid='44'"` <--注意周围缺少引号 (votes + 1)
Which doesn't run, but this SQL does do what I'm looking for:
"UPDATEusersSETvotes= (votes + 1) WHEREid= '44'"` <--Note the lack of quotes around (votes + 1)
有谁知道如何使用 codeigniter 的活动记录语法来实现这种类型的查询?
Does anyone know how to implement this type of query with codeigniter's active record syntax?
推荐答案
您可以按照以下操作:
$this->db->where('id', $post['identifier']);
$this->db->set('votes', 'votes+1', FALSE);
$this->db->update('users');
之所以有效，是因为第三个(可选)FALSE 参数告诉 CodeIgniter 不要用反引号 (') 保护生成的查询.这意味着生成的 SQL 将是:UPDATE users SET votes= votes + 1 WHERE id='44'
如果您注意到，从 '(votes+1)' 中删除了反引号，这会产生将 votes 属性增加 1 的预期效果.
The reason this works is because the third (optional) FALSE parameter tells CodeIgniter not to protect the generated query with backticks ('). This means that the generated SQL will be:
UPDATE users SET votes= votes + 1 WHERE id= '44'
If you notice, the backticks are removed from '(votes+1)', which produces the desired effect of incrementing the votes attribute by 1.
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