fix

blog/laravel/debugbar.md

+# Debugbar 调试器
+
+安装Debugbar
+
+```bash
+composer8 require barryvdh/laravel-debugbar
+```
+
+生成一个配置文件
+```bash
+php8 artisan vendor:publish --provider="Barryvdh\Debugbar\ServiceProvider"
+```
+
+页面底部的调试工具
+
+```php
+// @deprecated
+// use Barryvdh\Debugbar\Facade as DebugBar;
+use Barryvdh\Debugbar\Facades\Debugbar;
+
+DebugBar::info('信息!');
+```
+
+```php
+// config/debugbar.php
+
+// 关闭调试工具
+'enabled' => env('DEBUGBAR_ENABLED', false),
+```
+
+```php
+//手工开启或关闭 
+DebugBar::enable(); 
+DebugBar::disable();
+```
\ No newline at end of file

blog/laravel/index.md

@@ -36,7 +36,9 @@ dev:
 
 [集合 collection](/blog/laravel/collection.md)
 
-[模型的数据集合 ](/blog/laravel/model-collection.md)
+[模型的数据集合](/blog/laravel/model-collection.md)
 
-[模型关联 relation ](/blog/laravel/model-relation.md)
+[模型关联 relation](/blog/laravel/model-relation.md)
+
+[模型的关联查询](/blog/laravel/model-relation-query.md)
 

blog/laravel/model-preload.md

+# 模型的预加载
+
+预加载: 解决关联查询中产生的`N+1`次查询带来的资源消耗
+
+模型
+
+```php
+
+class User extends Model
+{
+    protected $table = 'user';
+    // 一对多关联 Book 表
+    public function books()
+    {
+        return $this->hasMany(Book::class, 'user_id', 'id');
+    }
+}
+
+
+class Book extends Model
+{
+    protected $table = 'book';
+
+    // 反向关联
+    public function user()
+    {
+        return $this->belongsTo(User::class, 'user_id', 'id');
+    }
+}
+
+```
+
+要获取所有书籍的作者(或拥有者)，普通查询方案如下
+
+```php
+//获取所有书籍列表 
+$books = Book::all();
+
+//遍历每一本书
+foreach ($books as $book) {
+    //每一本书的关联用户的姓名
+    DebugBar::info($book->user->username); 
+}
+```
+
+```sql
+-- N+1 条，就是起初获取全部数据的 1 条和，遍历的 N 条
+select * from `book`
+
+select * from `user` where `user`.`id` = ? limit 1
+select * from `user` where `user`.`id` = ? limit 1
+```
+
+使用with()关键字，进行预载入设置，提前将SQL整合
+
+```php
+//with 关键字预载入
+$books = Book::with('user')->get();
+
+foreach ($books as $book) { 
+    DebugBar::info($book->user->username);
+}
+```
+
+```sql
+select * from `book`
+
+select * from `user` where `user`.`id` in (1)
+```
+
+```php
+// 预载入设置指定的列
+$books = Book::with('user:id,name')->get();
+```
+
+```sql
+select * from `book`
+
+select `id`, `name` from `user` where `user`.`id` in (1)
+```
+
+模型中定义默认加载的关联
+
+```php
+class Book extends Model
+{
+    protected $table = 'book';
+
+    // 默认加载的关联
+    protected $with = ['user'];
+
+    // 反向关联
+    public function user()
+    {
+        return $this->belongsTo(User::class, 'user_id', 'id');
+    }
+}
+```
+
+预载入筛选
+
+```php
+Book::with([
+    'user' => function ($query) {
+        $query->where('id', 1);
+    }
+])->get();
+```
+
+```sql
+select * from `book`
+
+select * from `user` where `user`.`id` in (1) and `id` = ?
+```
+
+延迟预载入
+```php
+$books = Book::all();
+
+$books->load('user');
+```
+
+```sql
+select * from `book`
+
+select * from `user` where `user`.`id` in (1)
+```
+
+实现延迟关联统计
+```php
+$users = User::all();
+
+$users->loadCount('book');
+```
+
+```sql
+select * from `user`
+
+select `id`, 
+(
+    select count(*) from `book` where `user`.`id` = `book`.`user_id`
+) as `books_count` 
+from `user` 
+where `user`.`id` in (?, ?)
+```
+
+```json
+[
+    {
+        "id": 1,
+        "name": "曹真",
+        "age": 23,
+        "create_time": "2022-07-05 10:32:48",
+        "update_time": "2022-07-05 10:47:36",
+        "delete_time": null,
+        "books_count": 2
+    },
+    {
+        "id": 2,
+        "name": "曹丕",
+        "age": 21,
+        "create_time": "2022-07-05 10:36:47",
+        "update_time": "2022-07-05 10:47:22",
+        "delete_time": null,
+        "books_count": 0
+    }
+]
+
+```
\ No newline at end of file

blog/laravel/model-relation-query.md

+# 模型的关联查询
+
+```php
+
+class User extends Model
+{
+    protected $table = 'user';
+    // 一对多关联 Book 表
+    public function books()
+    {
+        return $this->hasMany(Book::class, 'user_id', 'id');
+    }
+}
+
+
+class Book extends Model
+{
+    protected $table = 'book';
+
+    // 反向关联
+    public function user()
+    {
+        return $this->belongsTo(User::class, 'user_id', 'id');
+    }
+}
+
+```
+
+查询
+
+```php
+//下面两种查询是一样的;
+$books = User::find(1)->books;
+
+$books = User::find(19)->book()->get();
+```
+
+```sql
+select * from `user` where `user`.`id` = ? limit 1
+
+select * from `book` where `book`.`user_id` = ? and `book`.`user_id` is not null
+```
+
+```php
+//可以采用 where 筛选或闭包 
+$books = User::find(1)
+    ->books()
+    ->where('id', 1)
+    ->orWhere('id', 11)
+    ->get();
+```
+```sql
+select * from `user` where `user`.`id` = ? limit 1
+
+select * from `book` where `book`.`user_id` = ? and `book`.`user_id` is not null and `id` = ? or `id` = ?
+```
+
+```php
+$books = User::find(1)
+    ->books()
+    ->where(function ($query) { 
+        $query->where('id', 1)->orWhere('id', 11);
+    })->get();
+```
+
+```sql
+select * from `user` where `user`.`id` = ? limit 1
+
+select * from `book` where `book`.`user_id` = ? and `book`.`user_id` is not null and (`id` = ? or `id` = ?)
+```
+
+has()方法，可以查询某些条件下的关联查询数据
+
+```php
+// 获取存在关联书籍的用户列表(言下之意:至少一本书) 
+$users = User::has('books')->get();
+```
+```sql
+select * from `user` where exists (
+    select * from `book` where `user`.`id` = `book`.`user_id`
+)
+```
+
+```php
+// 获取存在关联书籍(并超过 3 条)的用户列表 
+$users = User::has('book','>=', 3)->get(); 
+```
+
+```sql
+select * from `user` where (
+    select count(*) from `book` where `user`.`id` = `book`.`user_id`
+) >= 3
+```
+
+使用whereHas()方法，创建闭包查询
+
+```php
+//whereHas 闭包用法
+$users = User::whereHas('books', function ($query) {
+        //这里$query 是 book 表，通过 user_id 查询，返回 user 表数据
+        $query->where('user_id', 19); 
+    })->get();
+```
+```sql
+select * from `user` where exists (
+    select * from `book` where `user`.`id` = `book`.`user_id` and `user_id` = ?
+)
+```
+
+使用doesntHave()方法，即has()的反向操作
+
+```php
+// 获取不存在关联书籍的用户列表，闭包用法:whereDoesntHave() 
+$users = User::doesntHave('books')->get();
+```
+```sql
+select * from `user` where not exists (
+    select * from `book` where `user`.`id` = `book`.`user_id`
+)
+```
+
+使用withCount()方法，可以进行关联统计
+
+```php
+//关联统计，会自动给一个 book_count 字段 //统计每个用户有多少本书
+User::withCount('books')->get();
+```
+
+```sql
+select `user`.*,
+(select count(*) from `book` where `user`.`id` = `book`.`user_id`) as `books_count` 
+from `user`
+```
+```php
+// 给多个关系添加统计:profile_count，book_count
+User::withCount(['profile', 'books'])->get();
+```
+
+```sql
+select `user`.*, 
+(select count(*) from `profile` where `user`.`id` = `profile`.`user_id`) as `profile_count`, 
+(select count(*) from `book` where `user`.`id` = `book`.`user_id`) as `books_count` 
+from `user`
+```
+
+```php
+//关联统计再结合闭包进行筛选，还可以设置别名
+User::withCount(['profile', 'books' => function ($query) {
+        //这里限制被统计的记录
+        $query->where('user_id', 19); 
+    }])->get();
+```
+
+```sql
+select `user`.*, 
+(select count(*) from `profile` where `user`.`id` = `profile`.`user_id`) as `profile_count`, 
+(select count(*) from `book` where `user`.`id` = `book`.`user_id` and `user_id` = ?) as `books_count` 
+from `user`
+```
+
+https://www.bilibili.com/video/BV1gE411j78F?p=29&spm_id_from=pageDriver&vd_source=efbb4dc944fa761b6e016ce2ca5933da
\ No newline at end of file

blog/laravel/model-relation.md

@@ -621,5 +621,3 @@ where `user_role`.`user_id` = ? and `user_role`.`id` = ?
 - 多态一对多
 - 多态多对多
 
-
-https://www.bilibili.com/video/BV1gE411j78F?p=27&spm_id_from=pageDriver&vd_source=efbb4dc944fa761b6e016ce2ca5933da
\ No newline at end of file