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);
or
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