喜逢一个有你关于子查询的任何想法,我n codeigniter
这里是我的查询,我想将其转换成笨与笨子查询
SELECT question . *
FROM question
WHERE question.id NOT
IN (SELECT id
FROM answers)
喜逢一个有你关于子查询的任何想法,我n codeigniter
这里是我的查询,我想将其转换成笨与笨子查询
SELECT question . *
FROM question
WHERE question.id NOT
IN (SELECT id
FROM answers)
首先确保您有问题和答案,因为你之间的正确关系与回答表的ID匹配问题ID的混乱,也可以摆脱你的子查询,并可按加入
$this->db->select('q.*');
$this->db->from('question q');
$this->db->join('answers a','q.id=a.id','LEFT');/* make sure second parameter should match the question id from answer table */
$this->db->where('a.id IS NULL',null,FALSE);
$query = $this->db->get();
子查询可以放在一个字符串where子句中。
$this->db->select("question.*");
$this->db->where("question.id NOT IN (SELECT id FROM answers)");
$this->db->get('question');
$ this-> db-> select('question。*');
$ this-> db-> from('question');
$ this-> db-> where_not_in('question.id','(SELECT id FROM answers)',false);
$ result = $ this-> db-> get() - > result_array();
print_r($ result);
你好,欢迎来到StackOverflow!你能解释你的主张吗?此外,在每行代码的开头添加4个空格,以使该代码在此网站上变得更漂亮! (> [edit](https://stackoverflow.com/posts/48337998/edit))谢谢! – NatNgs
http://stackoverflow.com/questions/6047149/subquery-in-codeigniter-active-record –