how do I handle calculated fields in Laravel when using multiple databases

1. Use Eloquent's `saving` Event

You can use Eloquent's `saving` event to calculate fields just before they are saved to the database. This ensures that the calculated fields are updated correctly and consistently across the application[1][3].

2. Use a Service Class

For complex business logic that involves multiple calculations, you can create a service class that encapsulates the logic. This approach helps to separate the logic from the controllers and models, making the code more maintainable and reusable[3].

3. Use Raw SQL

For very complex calculations that involve raw SQL, you can use Laravel's raw query methods such as `selectRaw`, `whereRaw`, `havingRaw`, and `orderByRaw`. These methods allow you to inject raw SQL expressions into your queries, but be aware that they can introduce SQL injection vulnerabilities if not properly sanitized[2][5].

4. Use Laravel's `DB::statement` Method

For simple calculations that do not involve Eloquent models, you can use Laravel's `DB::statement` method to execute raw SQL queries. This method can be used for tasks such as updating tables or running SQL scripts[5].

5. Use Laravel's `DB::raw` Method

For more complex calculations that involve raw SQL, you can use Laravel's `DB::raw` method to include raw SQL expressions in your queries. This method allows you to specify a raw SQL expression that will be executed as part of the query[2].

Here is an example of using `selectRaw` to perform a complex calculation:

php
$orders = DB::table('orders')
    ->selectRaw('price * ? as price_with_tax', [1.0825])
    ->get();

In summary, the best approach depends on the complexity of the calculation and the requirements of your application. You can use Eloquent's `saving` event, a service class, raw SQL, `DB::statement`, or `DB::raw` methods, each with its own advantages and considerations.