ASP.NET -Advantages of LINQ

asp.netlinq

Recently I am using LINQ. But when facing an interview I am unable to explain:

What is LINQ?
Moreover, is DataSet deprecated due to the introduction of LINQ?

From an interview point of view, how should I answer those questions?

Best Answer

LINQ is a set of extensions to the .NET framework that enables language-integrated queries. This basically means that we can use the same type of syntax to query any set of data - whether it be a SQL database, Active Directory, or XML file - we can use the same syntax to execute queries.

The mechanism that LINQ uses to communicate with the different datasources is through providers - you can write your own provider if you wish, but the default providers are LINQ-to-Objects, LINQ-to-SQL and LINQ-to-XML. So again - LINQ allows you to use the same syntax for retrieving data from a SQL database, XML file or in-memory objects.

LINQ does not replace DataSets - in fact, you can use LINQ in conjunction with datasets. The only reason why there is a debate of DataSets vs LINQ is due to LINQ-to-SQL being an ORM. This means that we now have a choice in terms of built-in technologies for communicating with the database - previously datasets would be the default built-in option, now you can also opt for LINQ-to-SQL.

Related Solutions

C# – LINQ query on a DataTable

You can't query against the DataTable's Rows collection, since DataRowCollection doesn't implement IEnumerable<T>. You need to use the AsEnumerable() extension for DataTable. Like so:

var results = from myRow in myDataTable.AsEnumerable()
where myRow.Field<int>("RowNo") == 1
select myRow;

And as @Keith says, you'll need to add a reference to System.Data.DataSetExtensions

AsEnumerable() returns IEnumerable<DataRow>. If you need to convert IEnumerable<DataRow> to a DataTable, use the CopyToDataTable() extension.

Below is query with Lambda Expression,

var result = myDataTable
    .AsEnumerable()
    .Where(myRow => myRow.Field<int>("RowNo") == 1);

Linq – Multiple “order by” in LINQ

This should work for you:

var movies = _db.Movies.OrderBy(c => c.Category).ThenBy(n => n.Name)

Best Answer

Related Solutions

C# – LINQ query on a DataTable

Linq – Multiple “order by” in LINQ

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