小编sir*_*ius的帖子

我有一个充满坐标(x,y)的数据库,我希望找到最接近点的坐标.(可能有多个最接近这一点)

我已经写了这2个LINQ,但必须有一个聪明的方法,而不是通过数据库两次:

var closestDistance = _context.Coordinates.Min(x =>
                          Math.Sqrt(Math.Pow((point.coordX - x.CoordX), 2) +
                                    Math.Pow((point.coordY- x.CoordY), 2)));
var closest = _context.Coordinates.Where(x=> closestDistance ==
                          Math.Sqrt(Math.Pow((point.coordX - x.CoordX), 2) +
                                    Math.Pow((point.coordY - x.CoordY), 2)));

我该如何优化呢？

我有一些问题.我有2个班:Carorder:

<?php

namespace AppBundle\Entity;

use Doctrine\Common\Collections\ArrayCollection;
use Doctrine\ORM\Mapping as ORM;
use AppBundle\Entity\Orderdetail;

/**
 * @ORM\Entity
 * @ORM\Table(name="carorder")
 */
class Carorder
{
    /**
     * @ORM\Column(type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue
     */
    protected $id;
    /**
     * @ORM\OneToMany(targetEntity="Orderdetail", mappedBy="Carorder", cascade={"persist","remove"})
     **/
    protected $orderdetails;

    //Then all the auto genereted setters and getters beneath here

订单详情:

<?php

namespace AppBundle\Entity;

use Doctrine\ORM\Mapping as ORM;
use Doctrine\Common\Collections\ArrayCollection;

/** @ORM\Entity 
 *  @ORM\Table(name="orderdetail")
 */
class Orderdetail
{
     /**
     * @ORM\Column(type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue
     */
    protected $id;

    /**
     * @ORM\ManyToOne(targetEntity="Carorder", …