Getting Started with Linq Queries

Hi everyone in this blog I’m explaining about linq query.

Introduction:

Language-Integrated Query (LINQ) is a set of features introduced in Visual Studio 2008 that extends powerful query capabilities to the language syntax of C# and Visual Basic. LINQ introduces standard, easily-learned patterns for querying and updating data, and the technology can be extended to support potentially any kind of data store. Visual Studio includes LINQ provider assemblies that enable the use of LINQ with .NET Framework collections, SQL Server databases, ADO.NET Datasets, and XML documents.

Basic Query:

// To achieve Select * From ProductMst you need to write following linq Query

var Result1 = from p in db.ProductMst

select p;

// to achieve Select ProductID, ProductName, Price from ProductMst you need to write following linq Query

var Result2 = from p in db.ProductMst

Select new {

p.ProductID,

p.ProductName,

p.Price

};

Where Clause Query:

// to achieve Select * From ProductMst Where ProductID = 1 you need to write following linq Query

var Result3 = from p in db.ProductMst

Where p.ProductID == 1

Select p;

// to achieve Select * From ProductMst Where SupplierId =2 and Price > 10 you need to write following linq Query

var Result4 = from p in db.ProductMst

Where p.SupplierID == 2 && p.Price > 10

Select p;

// to achieve Select * From ProductMst Where SupplierId =2 Or SupplierId=5 you need to write following linq Query

var Result5 = from p in db.ProductMst

Where p.SupplierID == 2 || p.SupplierID == 5

Select p;

Order By Query:

//To achieve Select * From ProductMst Order By ProductId you need to write following linq Query

var Result6 = from p in db.ProductMst

orderby p.ProductID

select p;

// to achieve Select * From ProductMst Order By ProductId Desc you need to write following linq Query

var Result7 = from p in db.ProductMst

orderby p.ProductID descending

select p;

// to achieve Select * From ProductMst Order By CategoryId, Price Desc you need to write following linq Query

var Result8 = from p in db.ProductMst

orderby p.CategoryID, p.Price descending

Select p;

Top Query:

//To achieve Select Top 5 * From ProductMst you need to write following linq Query

var Result9 = (from p in db.ProductMst

Select p).Take (5);

//To achieve Select Top 1 * From ProductMst you need to write following linq Query

var Result10 = (from p in db.ProductMst

Select p).Take (1);

var Result11 = (from p in db.ProductMst

select p).First();

Distinct Query:

//To achieve Select Distinct CategoryId From ProductMst you need to write following linq Query

var Result13 = (from p in db.ProductMst

Select p.CategoryID).Distinct ();

Group By Query:

//To achieve Select CategoryId, Count(CategoryID) As FieldName From ProductMst Group By CategoryId you need to write following linq Query

var Result14 = from p in db.ProductMst

Group p by p.CategoryID into g

Select new {

CategoryId = g.Key,

FieldName = g.Count()

};

//To achieve Select CategoryId, Avg(UnitPrice) As NewField From ProductMst Group By CategoryId you need to write follofing linq Query

var Result15 = from p in db.ProductMst

group p by p.CategoryID into g

Select new {

CategoryId = g.Key,

FieldName = g.Average(S => S.Price)

};

Union Query:

//To achieve Select * From ProductMst Where CategoryId =1 union Select * From ProductMst Where CategoryId = 2 you need to write follofing linq Query

var Result17 = (from p in db.ProductMst

Where p.CategoryID == 1

Select p).Union (

From m in db.ProductMst

Where m.CategoryID == 2

Select m

);

in my next post i'll explain about Introduction of Troubleshooting

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