①、php原生sql写法：
　　$result = Db::query('select b.* from tp_admin a LEFT JOIN tp_cate b on(a.id= b.id) '); 

　　占位符写法：
    $result = Db::query('select * from tp_cate where id = :id',['id'=>$id]); 
　　拼接字符串：
　　 $sql = 'select * from t_admin where 1=1';
    $sql .= ' and nickname = '.$param['nickname'];
    $sql .= ' and create_time >= '.$param['start'];

②、thinkphp内置写法：
　　$result = model('admin')->select();

--------------------------------------------
渲染返回数据有区别的：

$dataview = [
    'allData' => $result,
];
$this->assign($dataview);
return view();
-------------------------------------------
前台js接受：

①、原生写法的渲染结果，报错 htmlentities() expects parameter 1 to be string, array given

<script>
    console.log('{$allData}'); //报错
</script>
　　解决方案：
　　php后台代码处理：(将数组类型转成JSON字符串)
　　　　$result = json_encode(Db::query('select b.* from tp_admin a LEFT JOIN tp_cate b on(a.id= b.id) '));

②、tp内置写法： 正确 渲染结果是string类型

<script>
    var xx = '{$allData}'
    console.log(typeof(xx)); //ok ，返回string类型
</script>

格式化输出：
　　$str =sprintf("sprintf输出：他名字叫%s,年龄是%u",'xiaohao',20);
结果：
　　sprintf输出：他名字叫xiaohao,年龄是20

 1 向session中存信息：
 2 session('admin',['id'=>$ret['id'],'nickname'=>$ret['nickname']]);
 3 获取session中的信息：
 4 session('admin.id') or session('admin')['id']
 5 
 6 ----------------------------------------------
 7 从request中获取信息
 8 $_GET['name'] or $_POST['name']
 9 ||
10 input('name')
11 -----------------------------------------------
12 判断请求类型
13 request()->isGet() //request()->isAjax()
总结：
$_SESSION 、 $_REQUEST 等貌似都可以用session() 和 request() 来调用

class User extends Validate
{
    protected $rule =   [
        'name'  => 'require|max:25',
　　　　　'password' => 'require',
        'age'   => 'number|between:1,120',
        'email' => 'email',    
    ];
    
    protected $message  =   [
        'name.require' => '名称必须',
　　　　 'name.max'     => '名称最多不能超过25个字符',
        'password.require' => '密码不能为空',
        'age.number'   => '年龄必须是数字',
        'age.between'  => '年龄只能在1-120之间',
        'email'        => '邮箱格式错误',    
    ];
　　
　　#上面的写法，可简写成如下(上面的写法信息更加具体) 
        protected $rule = [
            'name|用户名' => 'require|max:25',
　　　　　　　 'password|密码' => 'require',
            'age|年龄' => 'number|between:1,120',
            'email|邮箱' => 'email'
        ]; 
　
　　#可以定义场景，即使用指定的变量规则
　　public function  sceneLogin(){
       return $this->only(['name', 'password']);

　　}
}
---------------------------------------------------------------------------
使用：

$validate = new appindexvalidateUser;
#只使用自定义规则，不适用场景验证
if (!$validate->check($data)) {
    return $validate->getError();
}

#使用自定义验证场景，scene开头名字为login，调用的时候就使用
if (!$validate->sceneLogin()->check($data)) {
    return $validate->getError();
}
或者
if (!$validate->scene('login')->check($data)) {
    return $validate->getError();
}

1 修改config/app.php配置文件
2 // 控制器类后缀
3 'controller_suffix'      => true,
注意增加了这个之后，原本的Index.php就没用了，所以要访问首页，自己得创建一个IndexController.php

①、将json字符串转换成json数组对象
    $str = '[{"u6708u4efd":"201801","IPD":"9","POT":"25","PLC":"386","SEN":"202","INV":"168"},{"u6708u4efd":"201802","IPD":"8","POT":"10","PLC":"119","SEN":"125","INV":"40"},{"u6708u4efd":"201803","IPD":"6","POT":"35","PLC":"383","SEN":"214","INV":"200"},{"u6708u4efd":"201804","IPD":"22","POT":"33","PLC":"341","SEN":"243","INV":"130"},{"u6708u4efd":"201805","IPD":"10","POT":"38","PLC":"443","SEN":"240","INV":"135"},{"u6708u4efd":"201806","IPD":"4","POT":"20","PLC":"379","SEN":"266","INV":"130"},{"u6708u4efd":"201807","IPD":"7","POT":"16","PLC":"376","SEN":"341","INV":"132"},{"u6708u4efd":"201808","IPD":"0","POT":"0","PLC":"1","SEN":"0","INV":"0"}]';
    $jsonArr = json_decode($str);

②、将json数组转成json字符串
    $jsonArr = json_encode(Db::query('select DISTINCT  date from tp_data'));
    var_dump($jsonArr); 
    //string(136) "[{"date":1},{"date":2},{"date":3},{"date":4},{"date":5},{"date":6},{"date":7},{"date":8},{"date":9},{"date":10},{"date":11},{"date":12}]"

$where = array();
        if (!empty($status))
            $where[] = array('status', '=', $status);
        if (!empty($auid))
            $where[] = array('auid', '=', $auid);

$where = new Where();
        if ($start_time > 0 && $end_time > 0)
            $where['s.create_time'] = array('between', [$start_time, $end_time]);
        if (!empty($status))
            $where['s.status'] = array('=', $status);
        if ($user_id > 0)
            $where['s.auid'] = array('=', $user_id);