Laravel study notes (4) model, query

Laravel model read (original)

toArray can be transformed into an array
toSql can see the current query

1. Reading model of

   App\User::all();                          // 返回包含所有对象的集合
   
   // 以下方法虽然返回的是对象，但是直接可以以数组方式（如：$a[0]）取值
   \App\User::where('name', 'John')->first(); // 返回第一条数据的对象
   \App\User::where('id', 1)->value('name');   // 返回name字段的值（string）
    \App\User::find(3);                        // 返回主键等于 3 的对象
   \App\User::find([1, 2]);                   // 返回主键等于 1 和 2 的对象的集合
   \App\User::pluck('age');                   // 返回包含字段值的对象的集合
   \App\User::pluck('age', 'id');             // 返回关联对象的集合 id => age，pluck 最多 2 个参数
   \App\User::count();                        // 返回记录总数
   \App\User::max('id');                      // 返回数字，库没有任何记录返回 null
   \App\User::min('id');                      // 返回数字，库没有任何记录返回 null
   \App\User::avg('age');                     // 返回数字，库没有任何记录返回 null，同名 averge
   \App\User::sum('salary');                  // 返回数字，库没有任何记录返回 0
   

2. where

   where('votes', '=', 100)
   where('votes', 100)
   where('name', 'like', 'T%')
   where([
       ['status', '=', '1'],
       ['subscribed', '<>', '1'],
   ])
   where('votes', '>', 100)->orWhere('name', 'John')    // where votes > 100 or name = John
   whereBetween('votes', [1, 100])           // 包含了 1 和 100
   whereNotBetween('votes', [1, 100])
   whereIn('id', [1, 2, 3])
   whereNotIn('id', [1, 2, 3])
   whereNull('last_name')
   whereNotNull('updated_at')
   whereDate('created_at', '2016-12-31')   // where date(created_at) = '2016-12-31')
   whereMonth('created_at', '12')
   whereDay('created_at', '31')
   whereYear('created_at', '2016')
   whereTime('created_at', '=', '11:20:45')
   whereColumn('first_name', 'last_name')        // 判断两个字段 相等
   whereColumn('updated_at', '>', 'created_at')
   
   whereColumn([
       ['first_name', '=', 'last_name'],
       ['updated_at', '>', 'created_at']
   ])
   
   where('finalized', 1)->exists();      // 返回 true 或者 false
   // select exists(select * from `xxx` where `finalized` = 1) as `exists`
   where('finalized', 1)->doesntExist();
   // 运行的 SQL 和上面的一样，Laravel 把运行结果取反就达成目的了
   
   where('name', '=', 'John')
   ->orWhere(function ($query) {  // 传入闭包进 orWhere，避免全局 scope 产生不良影响
       $query->where('votes', '>', 100)
             ->where('title', '<>', 'Admin');
   })
   // where `name` = John or (`votes` > 100 and `title` <> Admin)
   
   whereExists(function ($query) {
       $query->selectRaw(1)
             ->from('orders')
             ->whereRaw('orders.user_id = users.id');
   })   
   // where exists ( select 1 from orders where orders.user_id = users.id )
   
   ->whereRaw('price > IF(state = "TX", ?, 100)', [200])->get();
   // IF 用法：IF(expr1,expr2,expr3)   
   // 如果 (expr1 <> 0 and expr1 <> NULL)，那么 expr1 就是 true。
   

3. select

   $users = \App\User::select('name', 'email as user_email')->get();
   
   $users = \App\User::distinct()->get();
   // select distinct * from `users1`
   
   $query = \App\User::select('name');
   $users = $query->addSelect('age')->get();
   // select `name`, `age` from `users`
   
   ->selectRaw('department, SUM(price) as total_sales')
   ->groupBy('department')
   ->havingRaw('SUM(price) > ?', [2500])
   ->orderByRaw('updated_at - created_at DESC')
   ->get();
   // select department, SUM(price) as total_sales from `destinations` group by `department` having SUM(price) > 2500 order by updated_at - created_at DESC
   

4. join

   # inner join
   ->join('contacts', 'users.id', '=', 'contacts.user_id')
   ->select('users.*', 'contacts.phone', 'orders.price')
   ->get();
   // select 'users.*', 'contacts.phone', 'orders.price' from users inner join 'contacts' on 'users.id' =  'contacts.user_id'
   
   # left join
   ->leftJoin('posts', 'users.id', '=', 'posts.user_id')
   ->get();
   
   # right join
   ->rightJoin('posts', 'users.id', '=', 'posts.user_id')
   ->get();
   
   # cross join
   ->crossJoin('colours')
   ->get();
   // 笛卡尔积
   
   # 高级 join
   ->join('contacts', function ($join) {
       $join->on('users.id', '=', 'contacts.user_id')->orOn('users.pid', '=', 'contacts.pid');
   })
   ->get();
   // select * from `users` 
   //     inner join 
   // `contacts` 
   //     on `users`.`id` = `contacts`.`user_id` or `users`.`pid` = `contacts`.`pid`
   
   
   ->join('contacts', function ($join) {
       $join->on('users.id', '=', 'contacts.user_id')
           ->where('contacts.user_id', '>', 5);		 // and `contacts`.`user_id` > 5
   })
   ->get();
   // select * from `users` inner join `contacts` 
   //     on
   // `users`.`id` = `contacts`.`user_id` and `contacts`.`user_id` > 5
   
   
   # union
   $first = App\User::whereNull('first_name');
   
   $users = App\Student::whereNull('last_name')
               ->union($first)
   
               ->get();
   // (select * from `students` where `last_name` is null) union (select * from `users` where `first_name` is null)
   
   # unionAll 和 union 参数一样
   // unionAll 不会去除重复值
   

5. Sorting, grouping and pagination

   orderBy('name', 'desc')
   
   latest()                // === orderBy('created_at', 'desc')
   
   inRandomOrder()
   // order by RAND()
   
   ->groupBy('account_id')->having('account_id', '>', 100)
   
   ->groupBy('site', 'qianjinyike.com')->having('account_id', '>', 100)
   
   skip(10)->take(5)        // 等价于 offset(10)->limit(5)
   // limit 5 offset 10