<?php
    namespace app\index\model;
    use think\Model;
    class User extends Model{
        public function getSexAttr($val){
            switch($val){
                case '1':
                    return "男";
                    break;
                case '2':
                    return "女";
                    break;
                default:
                    return "未知";
                    break;
            }
        }
    }

class Index extends Controller{
    public function index(){
        $res = User::count();
        $res = User::where('id','>','5')->count();
        $res = User::max('age');
        $res = User::sum('age');
        $res = User::min('age);
        $res = User::avg('age');//都可以和第一个一样带条件查询
        dump($res);
    }
}

<?php
    namespace app\index\controller;
    use think\Controller;
    use app\index\model\User;
    class index extends Controller{
        public function index(){
            $res = User::destroy(function($query){
                $query->where('id','>',5);
            });//可以传ID值或者闭包函数作为条件
            dump($res);
            $userModel = User::get(7);
            $userModel->delete();
            $res = User::where("1=1")
                ->delete();
            dump($res);
        }
    }

<?php
    namespace app\index\controller;
    use think\Controller;
    use app\index\model\User;
    class Index extends Controller{
        $data = [];
        for($i=1;$i<21;$i++){
            $data[] = [
                'username'=>'zhangsan_'.$i,
                'password'=>md5('sdfa'._$i),
                'age'=>$i
            ];
            $userModel = new User;
            $userModel->saveAll($data);
            dump($res);
            $res = User::update([
               'username'=>'wangba',
               'age'=>15,
               'id'=>15
            ],function($query){
                $query->where('id','LT',5);
            });//如果第一个参数不包含条件ID，第二个参数应该设置ID值或指闭包函数为更新条件
            dump($res);
            $res = User::where('id','<',6)
                ->update([
                    'username'=>'hehe'
                ]);
            $userModel = User::get(1);
            $userModel->username = "123";
            $userModel->age = 110;
            $usermodel = new User;
            $res = $userModel->save([
                'username'=>'huhu'
            ],function($query){
                $query->where("id","<","5");
            });
            $res = $usermodel->saveAll([
                ['id'=>1,'username'=>'jingyao'],
                ['id'=>2,'username'=>'lihong']
            ]);
        }
    }

<?php
    namespace app\index\controller;
    use think\Controller;
    use app\index\model\User;
    class Index extends Controller{
        public function index(){
            $user = User::create([
                'username'=>'zhangsan',
                'password'=>md5(123456),
                'age'=>13
            ],['username','age']);//第二个参数设置为true则只插入数据表中存在的字段，数组是允许插入的字段，不设置插入不存在的字段的时候会报错
            dump($res->id);//返回插入的ID
            $userModel = new User;
            $userModel->username = "lisi";
            $userModel->password = md5('sdfa');
            $userModel->save();
            dump($userModel->id);
            $userModel = new User;
            $res = $userModel
            ->allowField(['username'])
            ->save([
                "username"=>'wangba',
                'password'=>md5('sdfs'),
                'demo'=>123
            ]);
            $res = $userModel->saveAll([
                ['age'=>17],
                ['age'=>18]
            ]);
            foreach($res as $val){
                $arr = $val->toArray();
                dump($arr);
            }
        }
    }

<?php
    namespace app\index\controller;
    use think\Controller;
    use app\index\controller\User;
    class index extends Controller{
        $res = User::get(function($query){
            $query->where("username","eq","zhangsan")
                  ->filed("username,email");
        });
        $res = User::where("id",12)
            ->field("id,username")
            find();
         $res = User::all(function($query){
             $query->where("id","<","15")
                   ->select();
         });
         $res = User::where('id','>',"15")
              ->field("username,email")
              ->limit(3)
              ->order('id DESC')
              ->select();
         foreach($res as $val){
             $res->toArray();
             dump($val->toArray());
         }
         $res = User::value('email');
         $res = User::where('id','10')->value('email');
         $res = User::column("email","username");
         dump($res);
    }

<?php
    namespace app\index\controller;
    use think\Controller;
    use app\index\model\User;
    use think\Loader;
    class Index extends Controller{
        public function index(){
            $res = User::get(2);
            $user = new User;
            $res = $user::get(3);
            $user = Loader::model("User");
            $user = model("User");
            $res = $user::get(6);
            $res = $res->toArray();
            dump($res);
        }
    }

链式操作方法

$sql = $db->where('id','exp','not in (1,2,3)')->bulidSql();

eq  =    neq <>    lt <    elt <=    gt >    egt >=    between  notbetween    in    not in

$sql = $db->where("id",'lt','3')->buildSql();

$sql = $db->where('id','between','3,4')->buildSql();

$sql = $db->where('id','in',[1,2,3,41])->bulidSql();//in和between第三个参数可为数组或者字符串

$db->where()->delete();

$db->delete($id);

$db->where([])->update([])返回影响的行数

$db->where([])->setField($fieldname,$fieldvalue)更改某个字段值

$db->where([])->setInc($fieldname,$num);增加，不设置第二个参数默认为一

$db->where([])->setDec($fieldname,$num);减少

$db = Db::name(tablename);

$db->insert([]);返回插入记录行数；

$db->insertGetId([]);返回插入的自增ID；

$db->insertAll([[],[]]);返回批量插入数据成功的行数；

<?php
namespace app\index\controller;
use think\Controller;
use think\Db;
class Index extends Controller{  
    public function index(){
        dump(Config('database'));
        $res = Db::connect();
        $res = Db::connect([
            'type'=>'mysql',
            'hostname'=>'127.0.0.1',
            'database'=>'course',
            'usename'=>'root',
            'password'=>'root_pw',
            'hostport'=>'3306',
            'charset'=>'utf8',
            'prefix'=>''
        ]);
        $res=Db::connect('mysql://root:root@127.0.0.1:3306/course#utf8');
        dump($res);
    }

}

find返回的是一维数组，DB::name('表名')，DB::table('表全名')，db()助手函数第三个参数为false防止重新实例化