If you’re new to Laravel and working with Eloquent, you’ve probably seen two ways to “get unique records”: using distinct() or groupBy(). They may seem the same at first, but they behave differently — and this can be confusing for beginners. Let’s break it down.

Scenario

Suppose you have a reviews table with columns:

• id
• book_id
• review
• rating

You want to find books that have at least one 5-star review.

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Option 1: Using distinct()

$bookIds = Review::where('rating', 5)
    ->distinct()
    ->pluck('book_id');

What this does:

1. Filters reviews with rating = 5.
2. Returns only unique book_ids.
3. The pluck() method gives you a simple collection of IDs, not full models.

✅ Advantages:

• Simple and predictable.
• Always matches SQL SELECT DISTINCT book_id.
• Safe in strict SQL mode.

❌ Limitation:

• You cannot chain more query methods after pluck() because it executes immediately.

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Option 2: Using groupBy()

$reviews = Review::where('rating', 5)
    ->groupBy('book_id')
    ->get();

What this does:

1. Filters reviews with rating = 5.
2. Groups rows by book_id.
3. Returns full Eloquent models, including columns like review and created_at.

⚠️ Important:

• If you select all columns (*), MySQL in strict mode requires that all selected columns be aggregated or included in the GROUP BY.
• Laravel may return only the first review per book, which can make the row count different from SQL DISTINCT.

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Key Difference

Feature	distinct()->pluck('book_id')	groupBy('book_id')
Returns	Only unique IDs	Full models
Rows	Predictable	Can vary depending on SQL mode
Safe in strict SQL	✅	⚠️
Chainable after scope	❌	✅

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Pro Tips

1. Use distinct() if you only need unique values.
2. Use groupBy() if you want aggregates, like counting reviews per book:

Review::where('rating', 5)
    ->select('book_id', DB::raw('COUNT(*) as total_reviews'))
    ->groupBy('book_id')
    ->get();

3. Remember: Laravel scopes should return query builders, not executed results. This keeps them flexible and chainable.

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Conclusion

Many beginners get confused because:

• distinct() and groupBy() look similar.
• Laravel + strict MySQL mode may collapse rows differently.

Rule of thumb:

• IDs only → distinct()->pluck()
• Full models / counts → groupBy() with aggregation

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Understanding this difference helps you avoid bugs, mismatched row counts, and unexpected results when working with Eloquent.

Visual Example: Why distinct() and groupBy() Return Different Results

Let’s imagine we have a reviews table like this:

id	book_id	rating	review
1	10	5	Great book!
2	10	5	Loved it
3	11	5	Amazing story
4	12	4	Not bad
5	10	5	Highly recommend
6	13	5	Fantastic

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1️⃣ Using distinct()

$bookIds = Review::where('rating', 5)
    ->distinct()
    ->pluck('book_id');

SQL Generated:

SELECT DISTINCT book_id
FROM reviews
WHERE rating = 5;

Output:

book_id
10
11
13

✅ Exactly one row per book with 5-star reviews.
✅ Clean, predictable, no surprises.

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2️⃣ Using groupBy('book_id')

$reviews = Review::where('rating', 5)
    ->groupBy('book_id')
    ->get();

SQL Generated (simplified):

SELECT *
FROM reviews
WHERE rating = 5
GROUP BY book_id;

Output:

id	book_id	rating	review
1	10	5	Great book!
3	11	5	Amazing story
6	13	5	Fantastic

⚠️ Notice:

• Only one review per book is returned.
• If there were multiple 5-star reviews for a book (like book_id 10), the other reviews are “skipped”.
• The row count may look smaller than DISTINCT in some MySQL modes.

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Key Takeaways

1. distinct() → unique column values only (e.g., unique book IDs).
2. groupBy() → groups rows; other columns may be arbitrary unless you use aggregation (COUNT, MAX, etc.).
3. If you want all unique IDs → use distinct()->pluck().
4. If you want counts, averages, or sums per group → use groupBy() + aggregates.

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✅ Beginner-Friendly Rule

• IDs only → distinct()->pluck()
• Full rows with stats → groupBy() + aggregates