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超轻量级php框架startmvc

Laravel框架Eloquent ORM简介、模型建立及查询数据操作详解

更新时间:2020-04-13 22:25:46 作者:startmvc
本文实例讲述了Laravel框架EloquentORM简介、模型建立及查询数据操作。分享给大家供大家参考

本文实例讲述了Laravel框架Eloquent ORM简介、模型建立及查询数据操作。分享给大家供大家参考,具体如下:

注:以下知识点可能有不全面之处,望见谅

NO.1Eloquent ORM简介

Laravel所自带的Eloquent ORM是一个优美、简洁的ActiveRecord实现,用来实现数据库操作 每个数据表都有与之相对应的“模型(Model)”用于和数据交互

NO.2模型的建立

最基础的模型代码如下:


namespace App;
use Illuminate\Database\Eloquent\Model;
class Student extends Model
{
 //指定表名
 protected $table = 'student';
 //指定id
 protected $primaryKey = 'id';
}

将他创建于app目录下,命名为Student.php

NO.3查询数据

首先在查询之前,我先让你们看一下我的数据库

数据如上,然后查询

1.all方式

代码如下:


namespace App\Http\Controllers;
use App\Student;
use Illuminate\Support\Facades\DB;
class StudentController extends Controller
{
 public function orm1()
 {
 $students = Student::all();
 dd($students);
 }
}

显示数据库里的所有数据

2.find方式

代码如下:


namespace App\Http\Controllers;
use App\Student;
use Illuminate\Support\Facades\DB;
class StudentController extends Controller
{
 public function orm1()
 {
 $students = Student::find(1);
 dd($students);
 }
}

查找指定数据

3.findOrFail方式

代码如下:


namespace App\Http\Controllers;
use App\Student;
use Illuminate\Support\Facades\DB;
class StudentController extends Controller
{
 public function orm1()
 {
 $students = Student::findOrFail(1);
 dd($students);
 }
}

如果他没查到指定的数据,那么他会报错,而find若是没有查到该函数,只会弹出一个null

4.查询构造器的使用

  • 1.get方式使用

namespace App\Http\Controllers;
use App\Student;
use Illuminate\Support\Facades\DB;
class StudentController extends Controller
{
 public function orm1()
 {
 $students = Student::get();
 dd($students);
 }
}

他会得到一个完整的数据信息,和原本的意义没有区别

  • 2.first方式使用

代码如下:


namespace App\Http\Controllers;
use App\Student;
use Illuminate\Support\Facades\DB;
class StudentController extends Controller
{
 public function orm1()
 {
 $student = Student::where('id','>',1)
 ->orderBy('age','desc')
 ->first();
 dd($student);
 }
}

当id大于一的时候,获取一个最大值的age

  • 3.where方式使用

代码如下:


namespace App\Http\Controllers;
use App\Student;
use Illuminate\Support\Facades\DB;
class StudentController extends Controller
{
 public function orm1()
 {
 $student = Student::where('id','>',1)
 ->get();
 dd($student);
 }
}

  • 4.chunk方式使用

代码如下:


namespace App\Http\Controllers;
use App\Student;
use Illuminate\Support\Facades\DB;
class StudentController extends Controller
{
 public function orm1()
 {
 $student = Student::chunck(2,function($student){
 var_dump($student);
 });
 }
}

5.聚合函数的使用

  • 1.count函数

代码如下:


namespace App\Http\Controllers;
use App\Student;
use Illuminate\Support\Facades\DB;
class StudentController extends Controller
{
 public function orm1()
 {
 $student = Student::count();
 dd($student);
 }
}

  • 2.max函数

代码如下:


namespace App\Http\Controllers;
use App\Student;
use Illuminate\Support\Facades\DB;
class StudentController extends Controller
{
 public function orm1()
 {
 $student = Student::max('age');
 dd($student);
 }
}

  • 3.min函数

代码如下:


namespace App\Http\Controllers;
use App\Student;
use Illuminate\Support\Facades\DB;
class StudentController extends Controller
{
 public function orm1()
 {
 $student = Student::min('age');
 dd($student);
 }
}

  • 4.avg函数

代码如下:


namespace App\Http\Controllers;
use App\Student;
use Illuminate\Support\Facades\DB;
class StudentController extends Controller
{
 public function orm1()
 {
 $student = Student::avg('age');
 dd($student);
 }
}

  • 5.sum函数

代码如下:


namespace App\Http\Controllers;
use App\Student;
use Illuminate\Support\Facades\DB;
class StudentController extends Controller
{
 public function orm1()
 {
 $student = Student::sum('age');
 dd($student);
 }
}

Laravel Eloquent ORM 模型建立 查询数据