أسئلة القسم

An expression tree represents code as a data structure (an object graph).

LINQ providers like EF Core use them to translate C# expressions into SQL.

They live in System.Linq.Expressions.

In-memory (LINQ to Objects):

Operates directly on IEnumerable.

Uses C# delegates and executes in the CLR.

Example: List.Where(...) runs fully in memory.

Database (LINQ to Entities/SQL):

Operates on IQueryable.

Translates the expression tree into SQL.

Query executed on DB server, results materialized into objects

Example:

// In-memory
var local = list.Where(x => x > 10);  // runs in CLR

// EF Core -> SQL
var dbQuery = db.Users.Where(x => x.Age > 18); // translated to SELECT ... WHERE Age > 18

Key difference: Execution location (memory vs DB).