如何在codeigniter中编写此子查询select avg with limit

xienkqul 于 2021-06-21 发布在 Mysql

关注(0)|答案(1)|浏览(294)

SELECT AVG(harian) a from (select harian from sla limit 2) b

以上是在heidisql中执行的工作，
在下面试过：

$rata2 = $this->db->query('SELECT AVG(harian) a from (select harian from sla limit 2) b');

但是，好像没有输出，请帮忙，谢谢

mysql subquery codeigniter

来源：https://stackoverflow.com/questions/52257802/how-to-write-this-subquery-select-avg-with-limit-in-codeigniter

1条答案

按热度按时间

3zwtqj6y1#

// Sub Query
$this->db->select('harian')->from('sla')->limit(2);
$subQuery =  $this->db->get_compiled_select();

// Main Query
$rata2 = $this->db->select('AVG(harian)')
     ->from($subQuery)
     ->get();

return $rata2;

或者如果要返回数组中的数据

// Sub Query
$this->db->select('harian')->from('sla')->limit(2);
$subQuery =  $this->db->get_compiled_select();

// Main Query
$rata2 = $this->db->select('AVG(harian)')
     ->from($subQuery)
     ->get()
     ->toArray();

return $rata2;

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如何在codeigniter中编写此子查询select avg with limit

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