Summing over multiple fields in Laravel
Stefan Bogdanescu
Founder & Senior Architect · 2026-06-29
# Summing Over Multiple Fields in Laravel: Mastering Aggregation with the Fluent Query Builder
As developers working with relational databases through an ORM like Laravel's Eloquent, one of the most common challenges is moving from familiar SQL aggregation—like `SUM(column) GROUP BY...`—to achieving the same result using the fluent query builder. You are absolutely right to look for a direct equivalent when dealing with complex data summaries across relationships.
The core question is: Can we use Eloquent's fluent methods to perform multiple sums simultaneously in a single query? The short answer is yes, but it requires leveraging Eloquent’s relationship traits effectively. While you cannot chain `sum()` calls directly onto the main query builder like you might expect, Laravel provides powerful tools that abstract this complexity cleanly, often resulting in more readable and maintainable code than raw SQL joins for many scenarios.
Let's dive into how we can translate your desired SQL operation into idiomatic Laravel Eloquent.
## The Challenge: Aggregating Related Data
You have two models: `Event` and `Attendee`. You want to retrieve all events along with the total raised amount and total hours spent, grouped by event ID.
```sql
SELECT Event.id, sum(Attendees.total_raised), sum(Attendees.total_hours)
FROM Events JOIN Attendees ON Events.id = Attendees.event_id
GROUP BY Event.id
```
This requires a `JOIN` and a `GROUP BY`, which is the essence of aggregation. In Eloquent, this is typically handled through relationships.
## Solution 1: Using `withSum()` for Simple Aggregation
The most idiomatic Laravel way to handle one-to-many sums is by defining the relationship and using the `withSum()` method. This approach keeps the query clean and leverages Eloquent's ability to hydrate related data efficiently.
First, ensure your models are set up correctly:
```php
// app/Models/Event.php
class Event extends Model
{
public function attendees()
{
return $this->hasMany(Attendee::class);
}
// Define the sums you want to retrieve directly on the Event model
public function totalRaisedAttribute()
{
// This is often better handled via query scopes or accessor methods,
// but for simple sums, withSum works beautifully.
}
}
// app/Models/Attendee.php
class Attendee extends Model
{
public function event()
{
return $this->belongsTo(Event::class);
}
}
```
Now, in your controller or service layer, you can fetch the events and pre-calculate the sums:
```php
$events = Event::withSum('attendees', 'total_raised')
->withSum('attendees', 'total_hours')
->get();
// Result structure will look something like this (conceptually):
/*
[
{
"id": 1,
"total_raised": 500.00, // Calculated sum from attendees
"total_hours": 10.5 // Calculated sum from attendees
},
// ... other events
]
*/
```
The `withSum()` method tells Eloquent to perform a separate subquery for each specified relationship and aggregate the results back into the main query's result set, effectively performing the necessary joins and grouping behind the scenes. This is highly recommended when dealing with simple aggregations like sums, counts, or averages. For more complex queries involving multiple groupings, understanding how Eloquent builds these relationships is key, much like understanding the architecture behind tools found on platforms like [laravelcompany.com](https://laravelcompany.com).
## Solution 2: Advanced Aggregation with Raw Expressions (When `withSum` Isn't Enough)
If you need to perform more complex aggregations—for example, summing fields from *different* related tables or applying conditional logic within the grouping—you might need to step outside the simple `withSum()` structure and use raw expressions combined with joins.
While this moves slightly away from pure fluent query building, it gives you direct control over the SQL constructs you initially mentioned:
```php
$events = DB::table('events')
->join('attendees', 'events.id', '=', 'attendees.event_id')
->select(
'events.id',
DB::raw('SUM(attendees.total_raised) as total_raised'),
DB::raw('SUM(attendees.total_hours) as total_hours')
)
->groupBy('events.id')
->get();
```
This approach directly mirrors your original SQL query, is extremely fast for large datasets, and provides maximum flexibility. When performance or highly specific grouping logic becomes paramount, falling back to `DB::raw()` expressions combined with Eloquent's underlying database capabilities is a perfectly valid and often superior choice.
## Conclusion
For summing multiple fields across related models in Laravel, the best practice depends on complexity. Start with **`withSum()`** for standard one-to-many aggregations; it offers the cleanest, most Eloquent-centric solution. If you encounter scenarios requiring complex cross-table aggregation or advanced grouping logic, don't hesitate to use **`DB::raw()`** expressions to achieve precise control, ensuring you harness the full power of the underlying database while maintaining Laravel's structure. Mastering both methods will make you a more versatile and effective developer.