[英]Compare data from two tables in codeigniter
我有两个表(Comment&Evaluation),我想对codeigniter执行以下mySQL查询。 这是mySQL查询:
SELECT COUNT(DISTINCT source) AS NumberOfEvaluations
FROM COMMENT , EVALUATION
WHERE evaluation_id = EVALUATION.id AND EVALUATION.department_id = '$department_id' ;
这是我到达的目的地:
$this->db->select('count(DISTINCT(source))');
$this->db->from('comment','evaluation');
$this->db->where();
$query=$this->db->get();
return $query->num_rows();
我的问题是我应该在codeigniter的where子句中检查什么?
尝试运行以下代码:
$this->db->select('count(DISTINCT(source))');
$this->db->from('comment c','evaluation e');
$this->db->where('c.evaluation_id','e.id');
$this->db->where('e.department_id', $department_id);
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