Monday, 21 July 2014

What is LINQ? LINQ Queries to Show, Insert, Update, Search and Delete data from gridview in c# asp.Net.

Language Integrated Query (LINQ) is a Microsoft .NET Framework component that adds native data querying capabilities to .NET languages.

                      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.

LINQ has three major components:

1. LINQ to Objects
2. LINQ to ADO.NET, 3 sub parts
  •         LINQ to Dataset (originally called LINQ over Dataset)
  •         LINQ to Entities
  •         LINQ to SQL (originally called DLinq)

3. LINQ to XML (originally called XLinq)

LINQ to Objects deals with in-memory data. Any class that implements the IEnumerable<T> interface (in the System.Collections.Generic namespace) can be queried with SQO.

         LINQ to ADO.NET deals with data from external sources, basically anything ADO.NET can connect to. Any class that implements IEnumerable<T> or IQueryable<T> (in the System.Query namespace) can be queried with SQO.

           LINQ to XML is a comprehensive API for in-memory XML programming. Like the rest of LINQ, it includes SQO, and it can also be used in concert with LINQ to ADO.NET, but its primary purpose is to unify and simplify the kinds of things that disparate XML tools, like XQuery, XPath, and XSLT, are typically used to do. In this chapter we’ll preview LINQ to SQL and LINQ to DataSet, since they’re most closely related to the C# database programming we’ve covered in this book.

       1 Fill Data in Gridview:


public void showGridData()
{
LinqDataContext dataContaxt = new LinqDataContext ();
var q =from a in dataContaxt.GetTable<emp>()
select a;
GridView1.DataSource = q;
GridView1.DataBind();
}

 
      2 Search record:


public void SearchQuery()
{
LinqDataContext dataContaxt = new LinqDataContext ();
var q =
from a in dataContaxt.GetTable< emp >()
where a.name == TextBox3.Text
select a;
GridView1.DataSource = q;
GridView1.DataBind();
}

      3 Insert Record:


public void InsertQuery()
{
LinqDataContext dataContaxt = new LinqDataContext ();
emp objEmp = new emp ();
objEmp.name = TextBox3.Text;
objEmp.passw = TextBox5.Text;
objEmp.fname = TextBox4.Text;
dataContaxt.bios.InsertOnSubmit(objEmp);
dataContaxt.SubmitChanges();
showgridview();
}



      4 Update record:


public void UpdateQuery()
{
LinqDataContext dataContaxt = new LinqDataContext ();
emp objEmp = dataContaxt.emps.Single(emp => emp.name == TextBox3.Text);
objEmp.passw = TextBox5.Text;
objEmp.fname = TextBox4.Text;
objEmp.SubmitChanges();
}

       5 Delete Record:


public void DeleteQuery()
{
LinqDataContext dataContaxt = new LinqDataContext ();
emp objEmp = dataContaxt.bios.Single(emp => emp.name == TextBox3.Text);
dataContaxt.emps.DeleteOnSubmit(objEmp);
dataContaxt.SubmitChanges();
}

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