Reader Level:
ARTICLE

How to convert a simple DLINQ Query to a data set object

Posted by Bechir Bejaoui Articles | LINQ September 01, 2008
In this article I will represent a trick of how to convert a given DLINQ query to a data set object in order to make use of it as a data source for several controls such as grid view, data grid view and so forth.
  • 1
  • 0
  • 17147
Download Files:
 

In this article I will represent a trick of how to convert a given DLINQ query to a data set object in order to make use of it as a data source for several controls such as grid view, data grid view and so forth. As the Query object couldn't be directly used unless in very particular cases with particular controls. So I invite you to follow this walkthrough:

During this tutorial the NorthWind SQL Server data base is used as a data source. In order to download it you can reach it via this link

http://www.microsoft.com/downloads/details.aspx?FamilyID=06616212-0356-46A0-8DA2-EEBC53A68034&displaylang=en

Walkthrough:

  1. Create a new windows project and name it LinqQueyToDataSet

  2. Add a reference to the System.Data.Linq

    dlinq1.gif
     
    Figure 1

  3. Add a data grid view into the Form1 and set its Dock property to fill

  4. Add a reference to the System.Data.Linq.Mappinq that enables us to define Entity classes  witches are a sort of proxies' objects that represent the effective tables located in the NorthWind data base

  5. Add this entity class within the scope of the form1 class

    [Table(Name="Employees" )]
            class Employee
            {
                [Column(Name = "EmployeeID", IsPrimaryKey = true)]
                public int Identifier;
                [Column(Name = "LastName" )]
                public string LastName;
                [Column(Name = "FirstName" )]
                public string FirstName;
                [Column(Name = "Title")]
                public string Title;
                [Column(Name = "BirthDate")]
                public string BirthDate;
                [Column(Name = "Address" )]
                public string Address;
                [Column(Name = "City")]
                public string City;
                [Column(Name = "Country" )]
                public string Country;
            }

  6. Establish the connection to the NorthWind data base by defining a DataContext object as bellow

    DataContext oNorthWind = new DataContext(@"Data Source=STANDARD;Initial Catalog=" + @"C:\SQL SERVER 2000 SAMPLE DATABASES\NORTHWND.MDF';" +
      "Integrated Security=True"
    );

  7. Implement the load event handler of the Form1 as follow:
           
    private void Form1_Load(object sender, EventArgs e)
            {
                /* This is a simple DLinq Query that selects all rows from the
                   employee data table
                 */
                var Query = from emp in oNorthWind.GetTable<Employee>()
                            select emp;
                /*This command will get all inforamtion from the Query. The transformation
                  will be done thanks to the GetCommand of the data context object*/
                SqlCommand oCommand = oNorthWind.GetCommand(Query) as SqlCommand;
                //The data adapter will be used to  fill data
                SqlDataAdapter oAdapter = new SqlDataAdapter();
                //The rest is known....
                oAdapter.SelectCommand = oCommand;
                DataSet oDataSet = new DataSet();
                oAdapter.Fill(oDataSet);
                dataGridView1.DataSource = oDataSet;
                dataGridView1.DataMember = oDataSet.Tables[0].TableName;
            }

  8. Run the application now, and the result will be

    dlinq2.gif

    Figure 2

That's it.

God Dotneting!!!

COMMENT USING

Trending up