Laravel Development Services: The Complete Guide to Building Scalable Web Applications in 2026
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![Eager loading fixed your query count. It never fixed the hydration.
You write User::with('orders') so a table can show a last order date. Laravel runs two queries, then builds every Order model behind them. Fifty users with forty orders each is 2,000 objects created, cast and held in memory so you can read fifty timestamps.
A select subquery asks the database for the value instead of the rows.
User::addSelect(['last_order_at' => Order::select('created_at')
->whereColumn('user_id', 'users.id')
->latest()
->limit(1)])
Three rules that make it work:
1. One column, one row. select() a single column and limit(1), or the database rejects it.
2. Correlate with whereColumn and qualify the outer side as users.id. Plain where() compares against the literal string and quietly returns nothing.
3. What comes back is an attribute, not a relation. Cast it with withCasts(['last_order_at' => 'datetime']).
Then the payoff eager loading cannot reach: pass the same subquery to orderByDesc and you can sort a paginated list by a relation's value. Sorting the collection only reorders the page you already fetched, so your most recent customer stays on page 12.
One caveat, stated plainly: the subquery runs per candidate row, so index orders on (user_id, created_at). Without that index you have moved the cost, not removed it.
Keep with() when you need several fields, an accessor, or more than one related row. Reach for the subquery when you need one value.
Where in your codebase are you loading whole rows to read a single field?
#laravel #eloquent #php #backend #database sql performance laraveltips](https://laraveltips.io/wp-content/plugins/instagram-feed/img/placeholder.png)
