How to Count Query Results with `->count()`

Problem: You need to know how many records match your query criteria, but loading all records just to count them wastes memory and performance.

Solution:

// Count all records in a table
$userCount = User::count();

// Count with conditions
$activeUsers = User::where('active', true)->count();
$recentPosts = Post::where('created_at', '>', now()->subDays(7))->count();

// Count related records
$user = User::find(1);
$postCount = $user->posts()->count();
$publishedCount = $user->posts()->where('status', 'published')->count();

// Using withCount() for relationships
$users = User::withCount('posts')->get();
foreach ($users as $user) {
    echo $user->posts_count; // No additional queries
}

// Multiple counts
$users = User::withCount(['posts', 'comments'])->get();
$users = User::withCount([
    'posts',
    'posts as published_posts_count' => function ($query) {
        $query->where('status', 'published');
    }
])->get();

// Count vs Collection count()
// Database count (efficient)
$count = User::where('age', '>', 18)->count(); // SELECT COUNT(*)

// Collection count (inefficient for large datasets)
$count = User::where('age', '>', 18)->get()->count(); // Loads all records

Why it works: The query builder's count() executes a COUNT(*) SQL query, returning only the number without loading records into memory. withCount() adds a count subquery, preventing N+1 problems when counting relationships.

Performance tip: Always use query builder count() instead of collection count() when possible. For paginated results, use total() on the paginator.