php - 带有内连接的 Codeigniter 子查询

Question

我很难将 MySQL 查询转换为 Codeigniter 查询生成器。我无法与同一张表进行内部联接。就像我的 mySQL 查询一样。它正在 mySQL 上运行。这是我的查询:

$sql = "SELECT answers.* FROM answers INNER JOIN
                (SELECT * FROM
                    (SELECT employee_id as test_employee_id, created_on as test_created_on FROM answers) as test
                GROUP BY test.test_employee_id)
                AS test on (test.test_employee_id = answers.employee_id AND test.test_created_on = answers.created_on)
                ORDER BY answers.created_on DESC";

你们能帮我解决这个问题吗？我正在尝试将其转换为 Codeigniter 查询。

Answer 1

试试这个:

$this->db->select('answers.*');    
$this->db->from('answers');
$this->db->join('(SELECT * FROM
                    (SELECT employee_id as test_employee_id, created_on as test_created_on FROM answers) as test1
                GROUP BY test1.test_employee_id)
                AS test', 'test.test_employee_id = answers.employee_id AND test.test_created_on = answers.created_on');
$this->db->order_by("answers.created_on", "desc");
$query = $this->db->get(); 
return $query->result();