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Language Integrated Query By Nyros Developer


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Language Integrated Query By Nyros Developer

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Language Integrated Query By Nyros Developer

  1. 1. <ul><li>WELCOME TO ALL </li></ul>
  2. 2. LINQ <ul><li>Language Integrated Query provides built - in language querying functionality similar to SQL. </li></ul><ul><li>LINQ defines a set of standard query operators in the System.Linq namespace to select, filter, aggregate, and partition data. </li></ul><ul><li>LINQ is a new feature in Visual Studio 2008 and the .NET Framework 3.5 </li></ul>
  3. 3. Components in LINQ <ul><li>System.Linq C ontains the set of standard query operators and types and interfaces. </li></ul><ul><li>System.Data.Linq Contains classes that support interaction with relation data base. </li></ul><ul><li>System.Xml.Linq Contains classes for LINQ to XML </li></ul>
  4. 4. Operators in LINQ <ul><li>Average </li></ul><ul><li>Cast </li></ul><ul><li>ElementAt </li></ul><ul><li>ElementAtOrDefault </li></ul><ul><li>First </li></ul><ul><li>FirstOrDefault </li></ul><ul><li>Last </li></ul><ul><li>Reverse </li></ul><ul><li>Skip </li></ul><ul><li>SkipWhile </li></ul>
  5. 5. Example on Operators <ul><li>int[] nums = { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024 }; </li></ul><ul><li>int num1 = nums.First<int>(); </li></ul><ul><li>int num2 = nums.First<int>(x => x > 50); </li></ul><ul><li>int num3 = nums.FirstOrDefault<int>(x => x > 5000); </li></ul><ul><li>Console.WriteLine( </li></ul><ul><li>num1.ToString() + &quot;-&quot; + </li></ul><ul><li>num2.ToString() + &quot;-&quot; + </li></ul><ul><li>num3.ToString()); </li></ul>
  6. 6. LINQ Provider <ul><li>It is a gate for LINQ to act up on data that is not inside a queryable type. </li></ul><ul><li>1)Linq to Objects </li></ul><ul><li>2)Linq to XML </li></ul><ul><li>3)Linq to SQL </li></ul><ul><li>4)Linq to Datasets </li></ul>
  7. 7. LINQ to Objects <ul><li>string [] country = { &quot;India&quot; , &quot;China&quot; , &quot;America&quot; , &quot;Nepal&quot; }; IEnumerable < string > query =   from n in country                              where n.Length == 5                              orderby n descending                              select n; foreach ( string name in query) </li></ul><ul><li>{ </li></ul><ul><li>Response.Write(name.ToString()); </li></ul><ul><li>}            </li></ul>
  8. 8. LINQ to XML <ul><li>XElement countries = XElement .Parse(                @&quot;<countries>                    <country> India </country>                    <country> China </country>                    <country> America </country>                  </countries>&quot;             ); IEnumerable < string > query = from n in countries .Elements( &quot;country&quot; )                              where n.Value.Length == 5                              orderby n.Value descending                              select n.Value; </li></ul>
  9. 9. LINQ to SQL <ul><li>It allows .NET developers to write &quot;queries&quot; in their .NET language of choice. </li></ul><ul><li>The LINQ to SQL provider allows LINQ to be used to query SQL Server databases as well as Sql server compact database. </li></ul><ul><li>It has better support for server oriented features. </li></ul><ul><li>It is less complicated. </li></ul><ul><li>It has some what better performance. </li></ul>
  10. 10. <ul><li>SELECT ContactId, FirstName,LastName,DateOfBirth,Phone,Emai l </li></ul><ul><li>FROM [ Contact ] </li></ul><ul><li>WHERE DATEADD ( YEAR, @p0, DateOfBirth ) > @p1 </li></ul><ul><li>ORDER BY DateOfBirth DESC </li></ul><ul><li>DataContext db = new DataContext ( &quot;&quot; ); </li></ul><ul><li>var q = from c in db. Contact </li></ul><ul><li>where c. DateOfBirth . AddYears ( 35 ) > DateTime. Now </li></ul><ul><li>orderby c. DateOfBirth descending </li></ul><ul><li>select c; </li></ul>
  11. 11. LINQ on DataSets <ul><li>The DataSet is an in-memory representation of relational data </li></ul><ul><li>SqlDataAdapter da = new SqlDataAdapter( </li></ul><ul><li>&quot;SELECT * FROM Customers&quot;, </li></ul><ul><li>_connectionString); </li></ul><ul><li>DataTable customers = new DataTable(&quot;customers&quot;); </li></ul><ul><li>da.Fill(customers); </li></ul><ul><li>int countOfCustomers = </li></ul><ul><li>(from c in customers.AsEnumerable() </li></ul><ul><li>where c.Field<string>(&quot;Country&quot;) == &quot;France&quot; </li></ul><ul><li>select c).Count(); </li></ul>
  12. 12. Conclusion <ul><li>We can work on diverse data bases like Objects,SQL,DataSets.... </li></ul><ul><li>Provides consistency by defining a set of standard query operators </li></ul><ul><li>Deeply integrated into .Net languages </li></ul><ul><li>Intellisense for auto-completion </li></ul><ul><li>Performance is high </li></ul><ul><li>Compiler can perform syntax and type checking on query expressions </li></ul><ul><li>It is very powerful all on its own. </li></ul>
  13. 13. <ul><li>THANK YOU </li></ul>