Скачать или смотреть How to Convert Raw SQL Queries to Laravel Eloquent with the SUM Function

Learn how to effectively convert raw SQL queries to Laravel Eloquent, specifically focusing on using the `SUM` function to aggregate data in your applications.
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Converting Raw SQL Queries to Laravel Eloquent with the SUM Function

Using raw SQL queries in Laravel can be powerful, but when it comes to code maintainability and readability, using Eloquent ORM would be more advantageous. In this guide, we will discuss how to convert a raw SQL query that includes a SUM function into a structured Eloquent query.

The Problem

Imagine you have a raw SQL query that sums up the quantity of items in a shopping cart for a specific user. Here’s the original query:

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This query retrieves the total quantity of products in the cart, along with product details for a specific user, but it requires manual handling of database connections and makes your code less clean.

The Solution

To convert this to a Laravel Eloquent query, follow these steps. We will use the DB::table() method to organize our query.

Step 1: Setting Up the Query

You’ll want to start by joining the carts table with the products table to access all the necessary fields. Here's how:

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Step 2: Selecting Columns

Instead of selecting individual columns and then trying to apply the SUM function separately, you want to utilize DB::raw for aggregate functions. Here’s how you apply that:

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Step 3: Applying Conditions

Now, filter the results to only include records for the specified user using the where method:

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Step 4: Grouping and Ordering Results

Finally, you need to group the results by carts.productid to ensure that you get the sum of quantities per product, and order them as desired:

[[See Video to Reveal this Text or Code Snippet]]

Final Code Example

Putting it all together, your Eloquent query will look like this:

[[See Video to Reveal this Text or Code Snippet]]

Key Takeaways

Use DB::raw to execute aggregate functions like SUM along with other selected fields.

Organize your Eloquent queries by chaining methods for readability and maintainability.

Always test your queries to ensure that they return the expected results.

By converting your raw SQL queries to Eloquent, you not only make your code cleaner but also harness the full power of Laravel’s ORM features.

Now you can create more maintainable and readable code while working with databases in Laravel!