Write a query join sum groupby in laravel
Stefan Bogdanescu
Founder & Senior Architect · 2026-06-29
# Mastering Database Aggregation in Laravel: Joining, Summing, and Grouping
As senior developers working with the Laravel ecosystem, we frequently deal with complex data requirements that go beyond simple CRUD operations. One of the most common tasks involves aggregating data across multiple related tablesâa process that heavily relies on SQL's powerful `JOIN`, `SUM`, and `GROUP BY` clauses.
If you are trying to calculate the total debt grouped by currency, linked through project records, understanding how to translate this into efficient Laravel queries is essential. This post will walk you through exactly how to structure these complex queries effectively using Laravelâs Query Builder and Eloquent.
## Understanding the Requirement
Let's analyze the requirement: You have two tables, `projects` and `debts`. You need to calculate the sum of the `total` column from the `debts` table, grouped by the `currency_list`, linked via the `project_id`. The goal is to aggregate financial data based on currency.
The core SQL operation required is:
1. **JOIN:** Link `projects` and `debts`.
2. **GROUP BY:** Group the results based on a specific column (e.g., `currency_list`).
3. **SUM:** Calculate the total of the target column (`total`) within each group.
## Solution 1: Using the Laravel Query Builder
For complex aggregations, the raw power of the Query Builder often provides the most direct and performant route. We will use the `join`, `select`, `groupBy`, and `sum` methods provided by the facade.
Imagine we are working within a Controller or a dedicated service class in a Laravel application.
```php
use Illuminate\Support\Facades\DB;
class DebtService
{
public function getAggregatedDebts()
{
$results = DB::table('debts')
->join('projects', 'debts.project_id', '=', 'projects.id')
->select(
'debts.currency_list',
DB::raw('SUM(debts.total) as total_sum') // Use DB::raw for aggregate functions
)
->groupBy('debts.currency_list')
// Optional: Limit the result set if you only need a subset, like 1000 rows worth of groups
// ->limit(1000)
->get();
return $results;
}
}
```
### Explanation of the Query:
1. **`DB::table('debts')`**: We start the query from the table where the data we want to sum resides.
2. **`join('projects', 'debts.project_id', '=', 'projects.id')`**: This establishes the necessary link between the two tables using the foreign key relationship (`project_id`).
3. **`select('debts.currency_list', DB::raw('SUM(debts.total) as total_sum'))`**: We select the grouping column and use `DB::raw()` to instruct the database to calculate the sum of the `total` column for each group, aliasing it as `total_sum`.
4. **`groupBy('debts.currency_list')`**: This is crucial. It tells the database to collapse all rows with the same `currency_list` into a single summary row, allowing the `SUM()` function to operate on those groups correctly.
## Solution 2: Leveraging Eloquent Relationships (The Laravel Way)
While the Query Builder is excellent for raw aggregation, in a typical Laravel application, defining Eloquent relationships makes the code cleaner and more maintainable. If you have defined these relationships in your models, you can often leverage Eloquent's capabilities.
For very complex multi-level aggregations, sometimes hitting the database directly via the Query Builder (as shown above) is preferred for performance. However, if you needed to retrieve the related project details *alongside* the sum, Eloquent would shine:
```php
// Assuming models Project and Debt exist with proper relationships
$debtSummaries = Debt::with('project')
->select('currency_list', DB::raw('SUM(total) as total_sum'))
->groupBy('currency_list')
->get();
```
This approach demonstrates how powerful Laravel is in abstracting complex SQL into readable PHP code. For deeper insights into building robust database interactions, exploring the documentation provided by [laravelcompany.com](https://laravelcompany.com) on Eloquent and its underlying query methods is highly recommended.
## Conclusion
Mastering `JOIN`, `SUM`, and `GROUP BY` is fundamental to effective data management in Laravel. By understanding when to use the raw Query Builder for complex aggregations and when to leverage Eloquent relationships, you can write database queries that are not only correct but also performant and maintainable. Always aim for clarity; whether you use a direct SQL approach or an ORM wrapper like Laravel's tools, the goal is to retrieve exactly the data you need efficiently.