1. LINQ & ADO.NET Entity Framework*
1/14/201907/16/96
.NET Team
LINQ & ADO.NET Entity Framework
Stefan Dobrev GM
Avaxo Ltd.
(c) 2005 National Academy for Software Development - All rights reserved. Unauthorized copying or re-distribution is strictly prohibited.*

2. Contents LINQ – general stuff LINQ Providers ADO.NET Entity Framework*
1/14/201907/16/96
Contents
LINQ – general stuff
LINQ Providers
ADO.NET Entity Framework
(c) 2005 National Academy for Software Development - All rights reserved. Unauthorized copying or re-distribution is strictly prohibited.*

3. Language Integrated Query*
1/14/201907/16/96
LINQ
Language Integrated Query
(c) 2005 National Academy for Software Development - All rights reserved. Unauthorized copying or re-distribution is strictly prohibited.*

4. DEMO
LINQ in Action

5. Local variable type inference
What we saw?
Query
expressions
var func =
from l in ProgrammingLanguage.GetAll()
where l.Paradigm.HasValue(Functional)
select l;
Local variable type inference
var func =
ProgrammingLanguage.GetAll()
.Where(l => l.Paradigm.HasValue(Functional))
.Select(l => l);
Extension methods
Lambda expressions
Expression Trees

6. Local Variable Type Inference
int i = 5;
string s = "Hello";
double d = 1.0;
int[] numbers = new int[] {1, 2, 3};
Dictionary<int,Order> orders = new
Dictionary<int,Order>();
var i = 5;
var s = "Hello";
var d = 1.0;
var numbers = new int[] {1, 2, 3};
var orders = new
Dictionary<int,Order>();
Compiler infers the correct type from the right side

7. Bring extensions into scope
Extension Methods
obj.Foo(x, y) 
XXX.Foo(obj, x, y)
namespace ITBoxing {
public static class Extensions
public static string HasValue(
this ProgrammingParadigm paradigm,
ProgrammingParadigm value )
return ( paradigm & value ) != 0 }
Extension Method
Bring extensions into scope
using ITBoxing
IntelliSense
ProgrammingParadigm paradigm = Functional & Imperative;
Paradigm.HasValue(Imperative);

8. Lambda Expressions Lambda expression
List<ProgrammingLanguage> langs =
ProgrammingLanguage.GetAll();
List<ProgrammingLanguage> cool =
langs.FindAll(
delegate(ProgrammingLanguage l) {
return l.IsCool; } );
List<ProgrammingLanguage> langs =
ProgrammingLanguage.GetAll();
List<ProgrammingLanguage> cool =
langs.FindAll(l => l.IsCool);
Lambda expression

9. Expression Trees Code as Data
public delegate bool Predicate<T>(T item);
Expression<Predicate<ProgrammingLanguage>>
isCool = l => l.IsCool == true;
ParameterExpression l =
Expression.Parameter(
typeof(ProgrammingLanguage), "l" );
Expression expr =
Expression.Equal(
Expression.Property(l,
typeof(ProgrammingLanguage)
.GetProperty("IsCool")),
Expression.Constant(true));
Expression<Predicate
<ProgrammingLanguage>> isCool =
Expression.Lambda
<Predicate<ProgrammingLanguage>>(expr, l);

10. LINQ & ADO.NET Entity Framework
Questions?