What do you know about query builder in Laravel?

The Laravel Query Builder is a powerful and flexible tool for constructing and executing database queries in a fluent and expressive manner. It provides a convenient interface to perform most database operations, and it works seamlessly with all of Laravel's supported database systems. Here are some key points about the Laravel Query Builder:

Key Features

1. Fluent Interface:

   • The Query Builder provides a fluent interface, allowing you to chain methods to build complex queries in a readable and maintainable way. For example:
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     $users = DB::table('users')->where('votes', '>', 100)->get();

2. Security:

   • It uses PDO parameter binding to protect against SQL injection attacks. This means you don't need to manually sanitize user inputs when using the Query Builder[1][4][6].

3. Versatility:

   • The Query Builder can handle a wide range of database operations, including selects, inserts, updates, deletes, joins, unions, and more. It supports advanced features like conditional clauses, ordering, grouping, and pagination[4][6][7].

4. Raw Expressions:

   • While the Query Builder is designed to be safe and easy to use, it also allows for raw SQL expressions when necessary. This can be useful for complex queries that are difficult to express using the fluent interface[4][7].

5. Integration with Eloquent:

   • The Query Builder is often used in conjunction with Eloquent, Laravel's ORM. Eloquent models can use the Query Builder to perform database operations, providing a seamless integration between raw queries and ORM-based queries[5][8][9].

Examples

• Retrieving All Rows:

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

• Retrieving a Single Row:

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  $user = DB::table('users')->where('name', 'John')->first();

• Using Joins:

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

• Inserting Data:

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  DB::table('users')->insert([
      'email' => 'john@example.com',
      'name' => 'John'
  ]);

• Updating Data:

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  DB::table('users')
      ->where('id', 1)
      ->update(['votes' => 1]);

• Deleting Data:

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  DB::tab...