cakephp 检索数据

Question

我有 class 个，每个 class 个包含学生。 我想得到一个table包含每个class中的学生人数。 在这种情况下，如何找到：

$nums = $this->Student->find('count', array( 'group' => 'Student.Class_id'));

这个结果不正确

Answer 1

有几种存档方法：

1. 使用带查找所有的虚拟字段

   $this->Student->virtualFields = array('count' => 'COUNT(Student.' . $this->Student->primaryKey .')');
   $this->Student->find("all", array('fields' => 'count', 'group' => 'Student.Class_id'));
   

2. 构建自定义查询

   $this->Student->query("SELECT COUNT(Student.{$this->Student->primaryKey}) as 'count' FROM students Student GROUP BY Student.Class_id");