> ## Documentation Index
> Fetch the complete documentation index at: https://kawax.biz/llms.txt
> Use this file to discover all available pages before exploring further.

# Query Builder

> Basi e uso avanzato del Query Builder di Laravel con DB::table(). Come costruire SQL direttamente e quando usarlo al posto di Eloquent.

## Cos'è il Query Builder

Il Query Builder di Laravel offre un'interfaccia fluida per costruire ed eseguire query sul database. Parte da `DB::table()` e concatena i metodi.

```php theme={null}
use Illuminate\Support\Facades\DB;

$users = DB::table('users')->get();
```

Internamente usa il parameter binding di PDO, quindi la protezione da SQL injection è automatica.

<Info>
  Il Query Builder funziona su tutti i database supportati (MySQL, MariaDB, PostgreSQL, SQLite, SQL Server). Il codice non cambia cambiando database.
</Info>

## Quando usare il Query Builder o Eloquent

| Situazione                               | Consigliato   |
| ---------------------------------------- | ------------- |
| Servono modelli e relazioni              | Eloquent      |
| Aggregazioni e report complessi          | Query Builder |
| Prestazioni su grandi volumi             | Query Builder |
| Operazioni semplici su tabelle esistenti | Query Builder |
| Migration e seeder                       | Query Builder |

## Recupero dei dati

### Tutti i record

```php theme={null}
$users = DB::table('users')->get();

foreach ($users as $user) {
    echo $user->name;
}
```

`get()` restituisce `Illuminate\Support\Collection`. Ogni record è uno `stdClass`.

### Un solo record

```php theme={null}
$user = DB::table('users')->where('name', 'Mario Rossi')->first();
$user = DB::table('users')->where('name', 'Mario Rossi')->firstOrFail();
$email = DB::table('users')->where('name', 'Mario Rossi')->value('email');
$user = DB::table('users')->find(3);
```

### Elenchi di colonne

```php theme={null}
$emails = DB::table('users')->pluck('email');
$emailByName = DB::table('users')->pluck('email', 'name');
```

### Elaborazione a blocchi

```php theme={null}
use Illuminate\Support\Collection;

DB::table('users')->orderBy('id')->chunk(100, function (Collection $users) {
    foreach ($users as $user) {
        // ...
    }
});

DB::table('users')->where('active', false)
    ->chunkById(100, function (Collection $users) {
        foreach ($users as $user) {
            DB::table('users')
                ->where('id', $user->id)
                ->update(['active' => true]);
        }
    });
```

<Warning>
  Se aggiorni/elimini record mentre esegui `chunk`, usa `chunkById()` per evitare disallineamenti.
</Warning>

### Streaming (LazyCollection)

```php theme={null}
DB::table('users')->orderBy('id')->lazy()->each(function (object $user) {
    // Un utente alla volta
});
```

## Aggregazioni

```php theme={null}
$count   = DB::table('users')->count();
$maxAge  = DB::table('users')->max('age');
$minAge  = DB::table('users')->min('age');
$avgAge  = DB::table('users')->avg('age');
$total   = DB::table('orders')->sum('amount');

$avgPremium = DB::table('orders')
    ->where('plan', 'premium')
    ->avg('amount');
```

### Verifica esistenza

```php theme={null}
if (DB::table('orders')->where('finalized', 1)->exists()) {
    // Esiste
}

if (DB::table('orders')->where('finalized', 1)->doesntExist()) {
    // Non esiste
}
```

## SELECT

```php theme={null}
$users = DB::table('users')
    ->select('name', 'email as user_email')
    ->get();

$users = DB::table('users')->distinct()->get();

$query = DB::table('users')->select('name');
$users = $query->addSelect('age')->get();
```

## WHERE

### Condizioni base

```php theme={null}
$users = DB::table('users')->where('votes', 100)->get();
$users = DB::table('users')->where('votes', '>=', 100)->get();
$users = DB::table('users')->where('name', 'like', 'Mario%')->get();

$users = DB::table('users')
    ->where('status', 'active')
    ->where('age', '>', 20)
    ->get();

$users = DB::table('users')
    ->where('votes', '>', 100)
    ->orWhere('name', 'Mario Rossi')
    ->get();
```

### Raggruppamento

```php theme={null}
use Illuminate\Database\Query\Builder;

$users = DB::table('users')
    ->where('active', true)
    ->where(function (Builder $query) {
        $query->where('role', 'admin')
              ->orWhere('role', 'moderator');
    })
    ->get();
// WHERE active = 1 AND (role = 'admin' OR role = 'moderator')
```

### whereIn / whereBetween / whereNull

```php theme={null}
$users = DB::table('users')->whereIn('id', [1, 2, 3])->get();
$users = DB::table('users')->whereNotIn('id', [1, 2, 3])->get();

$users = DB::table('users')->whereBetween('age', [20, 40])->get();

$users = DB::table('users')->whereNull('deleted_at')->get();
$users = DB::table('users')->whereNotNull('email_verified_at')->get();
```

### whereLike

```php theme={null}
$users = DB::table('users')
    ->whereLike('name', '%Rossi%')
    ->get();

$users = DB::table('users')
    ->whereLike('name', '%Rossi%', caseSensitive: true)
    ->get();
```

### whereAny / whereAll

```php theme={null}
$users = DB::table('users')
    ->where('active', true)
    ->whereAny(['name', 'email', 'bio'], 'like', '%Laravel%')
    ->get();

$posts = DB::table('posts')
    ->whereAll(['title', 'content'], 'like', '%Laravel%')
    ->get();
```

### whereNullSafeEquals

`whereNullSafeEquals` (e `orWhereNullSafeEquals`) confronta considerando **due NULL come uguali**.

L'operatore `=` normale rende `NULL = NULL` come `false`; con `whereNullSafeEquals` invece i `NULL` sono uguali. Corrisponde a `<=>` di MySQL e `IS NOT DISTINCT FROM` di PostgreSQL.

```php theme={null}
$lastLoginIp = $request->input('last_login_ip');

$users = DB::table('users')
    ->whereNullSafeEquals('last_login_ip', $lastLoginIp)
    ->get();
```

<Info>
  Il classico `where('column', null)` diventa `WHERE column IS NULL`; `whereNullSafeEquals('column', $value)` funziona in modo coerente anche quando il valore associato è o non è `null`. Molto utile con input utente potenzialmente nullo.
</Info>

## JOIN

```php theme={null}
$users = DB::table('users')
    ->join('orders', 'users.id', '=', 'orders.user_id')
    ->select('users.name', 'orders.amount')
    ->get();

$users = DB::table('users')
    ->leftJoin('orders', 'users.id', '=', 'orders.user_id')
    ->get();

$users = DB::table('users')
    ->join('contacts', 'users.id', '=', 'contacts.user_id')
    ->join('orders', 'users.id', '=', 'orders.user_id')
    ->select('users.*', 'contacts.phone', 'orders.amount')
    ->get();
```

### JOIN con sottoquery

```php theme={null}
$latestOrders = DB::table('orders')
    ->select('user_id', DB::raw('MAX(created_at) as last_order_at'))
    ->groupBy('user_id');

$users = DB::table('users')
    ->joinSub($latestOrders, 'latest_orders', function ($join) {
        $join->on('users.id', '=', 'latest_orders.user_id');
    })
    ->get();
```

## Ordinamento, raggruppamento, limit

```php theme={null}
$users = DB::table('users')->orderBy('name', 'asc')->get();

$users = DB::table('users')
    ->orderBy('last_name')
    ->orderBy('first_name', 'desc')
    ->get();

$users = DB::table('users')->inRandomOrder()->get();

$orders = DB::table('orders')
    ->select('status', DB::raw('COUNT(*) as count'))
    ->groupBy('status')
    ->get();

$orders = DB::table('orders')
    ->select('user_id', DB::raw('SUM(amount) as total'))
    ->groupBy('user_id')
    ->having('total', '>', 10000)
    ->get();

$users = DB::table('users')
    ->skip(10)
    ->take(5)
    ->get();
```

## Sottoquery

```php theme={null}
$activeUsers = DB::table('users')->select('id')->where('is_active', 1);

$comments = DB::table('comments')
    ->whereIn('user_id', $activeUsers)
    ->get();

$users = DB::table('users')
    ->select('name')
    ->selectSub(function ($query) {
        $query->from('orders')
              ->selectRaw('COUNT(*)')
              ->whereColumn('orders.user_id', 'users.id');
    }, 'order_count')
    ->get();
```

## Espressioni Raw

<Warning>
  Le espressioni Raw vengono inserite come SQL. Passare input utente direttamente causa SQL injection. Usa sempre binding.
</Warning>

```php theme={null}
$users = DB::table('users')
    ->select(DB::raw('count(*) as user_count, status'))
    ->groupBy('status')
    ->get();

$orders = DB::table('orders')
    ->selectRaw('price * ? as price_with_tax', [1.10])
    ->get();

$orders = DB::table('orders')
    ->whereRaw('price > IF(state = "IT", ?, 100)', [500])
    ->get();

$orders = DB::table('orders')
    ->select('department', DB::raw('SUM(amount) as total'))
    ->groupBy('department')
    ->havingRaw('SUM(amount) > ?', [100000])
    ->get();

$orders = DB::table('orders')
    ->orderByRaw('updated_at - created_at DESC')
    ->get();
```

## INSERT / UPDATE / DELETE

### INSERT

```php theme={null}
DB::table('users')->insert([
    'email' => 'mario@example.com',
    'name'  => 'Mario Rossi',
]);

DB::table('users')->insert([
    ['email' => 'mario@example.com', 'name' => 'Mario Rossi'],
    ['email' => 'giulia@example.com', 'name' => 'Giulia Bianchi'],
]);

$id = DB::table('users')->insertGetId([
    'email' => 'luca@example.com',
    'name'  => 'Luca Verdi',
]);
```

### UPSERT

```php theme={null}
DB::table('users')->upsert(
    [
        ['email' => 'mario@example.com', 'name' => 'Mario Rossi', 'votes' => 5],
        ['email' => 'giulia@example.com', 'name' => 'Giulia Bianchi', 'votes' => 10],
    ],
    uniqueBy: ['email'],
    update: ['name', 'votes']
);
```

### UPDATE

```php theme={null}
$affected = DB::table('users')
    ->where('id', 1)
    ->update(['name' => 'Mario R.', 'updated_at' => now()]);

DB::table('users')->where('id', 1)->increment('votes');
DB::table('users')->where('id', 1)->increment('votes', 5);
DB::table('users')->where('id', 1)->decrement('votes');
DB::table('users')->where('id', 1)->decrement('balance', 100);
```

### DELETE

```php theme={null}
$deleted = DB::table('users')->where('status', 'inactive')->delete();

DB::table('users')->truncate();
```

## Query condizionali (when)

```php theme={null}
$status = request('status');
$sortBy = request('sort', 'name');

$users = DB::table('users')
    ->when($status, function ($query, $status) {
        $query->where('status', $status);
    })
    ->when($sortBy === 'email', function ($query) {
        $query->orderBy('email');
    }, function ($query) {
        $query->orderBy('name');
    })
    ->get();
```

## Debug

```php theme={null}
$sql = DB::table('users')->where('active', true)->toSql();
$bindings = DB::table('users')->where('active', true)->getBindings();

DB::table('users')->where('active', true)->dump();
DB::table('users')->where('active', true)->dd();
```

<Tip>
  `dd()` è comodo in debug ma non usarlo in produzione. `toSql()` e `getBindings()` sono più sicuri.
</Tip>

## Riepilogo

<AccordionGroup>
  <Accordion title="Metodi più usati">
    | Metodo                    | Descrizione                  |
    | ------------------------- | ---------------------------- |
    | `get()`                   | Tutti i record (Collection)  |
    | `first()`                 | Primo record                 |
    | `find($id)`               | Per ID                       |
    | `value($column)`          | Valore di una colonna        |
    | `pluck($column)`          | Elenco valori di una colonna |
    | `count()`                 | Conteggio                    |
    | `sum($col)`               | Somma                        |
    | `avg($col)`               | Media                        |
    | `max($col)` / `min($col)` | Massimo/minimo               |
    | `exists()`                | Verifica esistenza           |
    | `insert([...])`           | Insert                       |
    | `update([...])`           | Update                       |
    | `delete()`                | Delete                       |
    | `chunk($n, fn)`           | A blocchi                    |
    | `when($cond, fn)`         | Condizionale                 |
    | `toSql()`                 | Verifica SQL                 |
  </Accordion>

  <Accordion title="Query Builder vs Eloquent">
    Il Query Builder è più a basso livello e restituisce `stdClass`.
    Se non ti servono relazioni ed eventi dei modelli è più semplice e veloce.

    ```php theme={null}
    // Eloquent
    $users = User::where('active', true)->get();
    echo $users[0]->name; // Istanza User

    // Query Builder
    $users = DB::table('users')->where('active', true)->get();
    echo $users[0]->name; // stdClass
    ```
  </Accordion>
</AccordionGroup>


## Related topics

- [MongoDB](/it/mongodb.md)
- [Configurazione del database](/it/database.md)
- [Trait ForwardsCalls](/it/advanced/forwards-calls.md)
- [Attributi PHP](/it/advanced/php-attributes.md)
- [Riepilogo delle novità di Laravel 13](/it/blog/laravel-13-new-features.md)