一张分类表
一张分类具体数据表 [ 一个分类多条数据]
目的:
查询分类表, 获取每个分类下的最新的一条数据
coding:
controller:
$model = new AluCategory();
$list = $model->with('today')->select();
model :
public function today($query)
{
return $this->hasMany('AluRecord', 'category_id')
->order('day desc')
->limit(1);
}
Log:
[ sql ] [ SQL ] SHOW COLUMNS FROM `alu_category` [ RunTime:0.013016s ]
[ sql ] [ SQL ] SELECT * FROM `alu_category` [ RunTime:0.000497s ]
[ sql ] [ SQL ] SHOW COLUMNS FROM `alu_record` [ RunTime:0.012264s ]
[ sql ] [ SQL ] SELECT * FROM `alu_record` WHERE `category_id` IN (1,2,3,4,5,6,7,8,9,10,11,12,13) ORDER BY[b][/b] LIMIT 1 [ RunTime:0.003616s ]
问题:
day desc 在sql 中出现了两次. 如果直接使用预加载 是就是好的.
最佳答案
