Question

Please keep in mind that I’m new to C# and OOP so I apologize in advance if this seems like an easy question to some. I’m going back through my code and looking for ways to objectify repetitive code and create a class for it so that I can simply reuse the class. That being said, I’m not looking to learn NHibernate or any other ORM just yet. I’m not even looking to learn LINQ. I want to hack through this to learn.

Basically I use the same bit of code to access my database and populate a drop-down list with the values that I get. An example:

   protected void LoadSchools()     {         SqlDataReader reader;          var connectionString = ConfigurationManager.ConnectionStrings['MyConnectionString'].ConnectionString;         var conn = new SqlConnection(connectionString);         var comm = new SqlCommand('SELECT * FROM [Schools] ORDER BY [SchoolName] ASC', conn);          try         {             conn.Open();             reader = comm.ExecuteReader();             cmbEditSchool.DataSource = reader;             cmbEditSchool.DataBind();               cmbEditSchool.Text = 'Please select an existing school to edit...';             if (reader != null) reader.Close();         }          finally         {             conn.Dispose();         }     } 

I use this same bit of code, over and over again throughout my program, on different pages. Most often, I’m populating a drop-down list or combo box, but sometimes I will populate a gridview, only slightly altering the query.

My question is how can I create a class that will allow me to call a stored procedure, instead of manually using queries like my example, and populate my different controls? Is it possible to do with only 1 method? I only need to start with selects. I’ve been reading up on IEnumerable which seems like the appropriate interface to use, but how do I use it?

Edited to add:

I marked Rorschach’s answer as THE answer because s/he addressed my IEnumerable question. I also understand the need for a proper DAL and perhaps BLL layer. What I was trying to get to was that. I can build a DAL using datasets and table adapters which, in the end, gets me a strongly typed dataset. However, I feel a bit removed from the code. I was after a straight-forward way of building the DAL myself starting with the code that I gave above. Perhaps I’m not wording my question, or what I’m after, correctly.

At any rate, Rorschach came closest to answering my actual question. Thanks.

Answer 1

You can create a class that lets you call stored procedures (this is known as a Data Access Component (DAC) class, which is usually referenced by a Business Component (BC) class, but it is outside the scope of your question).

There are a few objects you will want to use in this new class: Microsoft.Practices.EnterpriseLibrary.Data.Database Microsoft.EnterpriseLibrary.Data.DatabaseFactory System.Data.Common.DBCommand

The DAC class will look similar to what you have:

public class DataAccess {     public DataAccess()     {     }     public System.Collections.IEnumerable GetSchoolData()     {         string connectionString = ConfigurationManager.ConnectionStrings['MyConnectionString'].ConnectionString;         Database db = DatabaseFactory.CreateDatabase(connectionString);         string sqlCommand = 'GetSchoolData';         DbCommand comm = db.GetStoredProcCommand(sqlCommand);         //db.AddInParameter(comm, 'SchoolId', DbType.Int32); // this is in case you want to add parameters to your stored procedure          return db.ExecuteDataSet(comm);     } } 

And your page code will look like this:

public class SchoolPage : Page {   public void Page_Init(object sender, EventArgs e)   {     DataAccess dac = new  DataAccess();     cmbEditSchool.DataSource = dac.GetSchoolData();     cmbEditSchool.DataBind();   } } 

Note that this is just to help you learn how to do this. It is not a good approach to development because you are opening up your Data Access Layer to the outside world (which is bad).