LINQ and Collections

1. What does the `IEnumerable<T>` interface allow C# developers to do?

Execute SQL queries directly on databases Iterate over a sequence of data in memory Build expression trees for deferred execution Perform grouping and aggregation operations directly

2. What is the key difference between `IQueryable<T>` and `IEnumerable<T>`?

`IQueryable<T>` executes queries immediately while `IEnumerable<T>` does not `IQueryable<T>` holds an expression tree while `IEnumerable<T>` executes code directly `IEnumerable<T>` supports database querying while `IQueryable<T>` does not `IQueryable<T>` is always in memory while `IEnumerable<T>` can be remote

3. Why is it important to sort before using pagination methods like `Skip` or `Take`?

To avoid SQL errors To ensure stable results across database queries To improve performance on large datasets To make grouping operations faster

4. What is a common pitfall when using LINQ queries, especially with `IQueryable`?

Returning too many records Inadequate filtering conditions Multiple enumeration of a query may cause performance issues Using the wrong method for projection

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