Rule Definition
Using .Count() to check if a collection or queryable contains any elements is less efficient than using .Any(). Count() enumerates the entire collection (or issues SELECT COUNT(*) in SQL) Any() stops at the first match (or generates SELECT TOP 1 1 WHERE EXISTS(...) in SQL) This makes Any() faster, especially with large datasets or expensive queries.

Remediation
Replace checks like if (collection.Count() > 0) with if (collection.Any()). Exceptions & Notes Use Count() only when you actually need the number of elements. Any() is only for existence checks (i.e., “at least one?”). if (collection.Count() > 0) replace by if (collection.Any()) if (collection.Count() == 0) replace by if (!collection.Any())

Violation Code Sample

if (dbContext.Users.Count() > 0) //⚠️ VIOLATION
{
    Console.WriteLine("Users exist");
}

// OR

if (list.Count() > 0) { ... } //⚠️ VIOLATION

Fixed Code Sample

if (dbContext.Users.Any())  // ✓ FIXED
{
    Console.WriteLine("Users exist");
}

// OR

if (list.Any()) { ... } // ✓ FIXED

https://learn.microsoft.com/en-us/dotnet/fundamentals/code-analysis/quality-rules/ca1827