Oledb and sql provider parameter treatment

SQL provider - The creation of the parameters is name-dependent and not order-dependent.

OleDb provider - The creation of the parameters is order-dependent and not order dependent.

 

 

 

 

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Using parentheses with object initializers

public class ClassWithDefaultConstructor

{

    public string Property { get; set; }

}

public class ClassWithConstructorWithParameters

{

    public ClassWithConstructorWithParameters(string property)

    {

        this.Property = property;

    }

    public string Property { get; set; }

}

   

Correct usages -

var c = new ClassWithDefaultConstructor { Property = "value" };

var c = new ClassWithDefaultConstructor() { Property = "value" };

var c = new ClassWithConstructorWithParameters() { Property = "value" };

 

Wrong usage -

var c = new ClassWithConstructorWithParameters { Property = "value" };

 

Reason -

If you are using a parameterless constructor, as shown, the parentheses are optional, but if you are executing a constructor that requires parameters, the parentheses are mandatory, o/w, the compiler would cry as below -
 

Compile error -

'LINQProcessing.ClassWithConstructorWithParameters' does not contain a constructor that takes 0 arguments

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Joins-to-C# Query Extension Methods Mapping

Joins and their corresponding LINQ Query Extension methods

Type of join	Query extension method	Example	Example Result (By enumerating through the query variable and displaying the details on console)
Inner Join	Join	var makes = new string[] { "Audi", "BMW", "Ford", "Mazda", "VW" }; var cars = GetCars(); var query = makes.Join(cars, make => make, car => car.Make, (make, innerCar) => new { Make = make, Car = innerCar });	Make: Audi, Car:ABC456 Audi TT Make: BMW, Car:DEF123 BMW Z-3 Make: Ford, Car:ABC123 Ford F-250 Make: Ford, Car:DEF456 Ford F-150 Make: VW, Car:HIJ123 VW Bug
Left Outer Join	GroupJoin	var makes = new string[] { "Audi", "BMW", "Ford", "Mazda", "VW" }; var cars = GetCars(); var query = makes.GroupJoin(cars, make => make, car => car.Make, (make, innerCars) => new { Make = make, Cars = innerCars });	Make: Audi Car VIN:ABC456, Model:TT Make: BMW Car VIN:DEF123, Model:Z-3 Make: Ford Car VIN:ABC123, Model:F-250 Car VIN:DEF456, Model:F-150 Make: Mazda Make: VW Car VIN:HIJ123, Model:Bug
Cross Join (Cartesian product)	SelectMany	var repairs = new List<Tuple<string, List<string>>> { Tuple.Create("ABC123", new List<string>{"Rotate Tires","Change oil"}), Tuple.Create("DEF123", new List<string>{"Fix Flat","Wash Vehicle"}), Tuple.Create("ABC456", new List<string>{"Alignment","Vacuum", "Wax"}), Tuple.Create("HIJ123", new List<string>{"Spark plugs","Air filter"}), Tuple.Create("DEF456", new List<string>{"Wiper blades","PVC valve"}), }; var query = repairs.SelectMany(t => t.Item2.Select(r => new { VIN = t.Item1, Repair = r }));	VIN:ABC123 Repair:Rotate Tires VIN:ABC123 Repair:Change oil VIN:DEF123 Repair:Fix Flat VIN:DEF123 Repair:Wash Vehicle VIN:ABC456 Repair:Alignment VIN:ABC456 Repair:Vacuum VIN:ABC456 Repair:Wax VIN:HIJ123 Repair:Spark plugs VIN:HIJ123 Repair:Air filter VIN:DEF456 Repair:Wiper blades VIN:DEF456 Repair:PVC valve

Extension method syntax - [source collection].[extension method].[extension method]…;

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