dataadapter2.cs

Professional C# 2nd Edition

using System;
using System.Data;
using System.Xml;
using System.Data.SqlClient;
using System.Data.OleDb;

/// <summary>
/// Corresponds to section titled 'Updating via DataAdapters' in Chapter 11
/// </summary>
public class DataAdapter
{
	/// <summary>
	/// DataAdapter2 - show Stored Procs and DataAdapter
	/// </summary>
	public static void Main ( )
	{
		// The following is the database connection string
		string			source = Login.Connection;

		// Create & open the database connection
		SqlConnection	conn = new SqlConnection ( source ) ;
		conn.Open ( ) ;

		// Create a DataSet
		DataSet		ds = new DataSet ( ) ;

		// Create a Region DataTable
		CreateTable ( ds ) ;

		// Create a data adapter to fill the DataSet
		SqlDataAdapter	da = new SqlDataAdapter ( ) ;

		// Set the data adapters select co
		da.SelectCommand = GenerateSelectCommand ( conn ) ;
		da.InsertCommand = GenerateInsertCommand ( conn ) ;
		da.UpdateCommand = GenerateUpdateCommand ( conn ) ;
		da.DeleteCommand = GenerateDeleteCommand ( conn ) ;

		// Execute the Select Command to fill the dataset
		da.Fill ( ds , "Region" ) ;

		DumpDataSet ( ds , "Initial data selected from database" ) ;

		// Add a new row into the dataset
		DataRow	r = ds.Tables["Region"].NewRow() ;
	
		r["RegionID"]=999;
		r["RegionDescription"]="North West" ;

		// Add the row into the DataTable
		ds.Tables["Region"].Rows.Add ( r ) ;

		DumpDataSet ( ds , "New row pending inserting into database" ) ;

		// And use the data adapter to update the table
		da.Update ( ds , "Region" ) ;

		DumpDataSet ( ds , "New row updated and new RegionID assigned by database" ) ;

		// Capture the regionID for later...
		string	regionID = r[0].ToString ( ) ;

		// Now update something that's already there
		r["RegionDescription"]="North West England";

		DumpDataSet ( ds , string.Format ( "Changed RegionID {0} description" , regionID ) ) ;

		// And use the data adapter to update the table
		da.Update ( ds , "Region" ) ;

		// And finally delete the row I added...
		r.Delete();

		DumpDataSet ( ds , string.Format ( "Deleted RegionID {0}" , regionID ) ) ;

		// And use the data adapter to update the table
		da.Update ( ds , "Region" ) ;

		// Example .XML files used late in this chapter.
		ds.WriteXml ( ".\\WithoutSchema.xml" ) ;
		ds.WriteXml ( ".\\WithSchema.xml" , XmlWriteMode.WriteSchema ) ;
	}

	/// <summary>
	/// Dump the contents of the dataset to the console
	/// </summary>
	/// <param name="ds">The dataset</param>
	/// <param name="message">A message to output</param>
	private static void DumpDataSet ( DataSet ds , string message )
	{
		Console.WriteLine ( message ) ;

		foreach ( DataRow aRow in ds.Tables["Region"].Rows )
		{
			if ( aRow.RowState == DataRowState.Deleted )
				Console.WriteLine ( "Row Deleted" ) ;
			else
				Console.WriteLine ( "  {0,-3} {1,-50} {2}" , aRow[0] , aRow[1] , aRow.RowState ) ;
		}
	}

	/// <summary>
	/// Create a command that will select all region records
	/// </summary>
	/// <param name="conn">The database connection</param>
	/// <returns>A SqlCommand</returns>
	private static SqlCommand GenerateSelectCommand ( SqlConnection conn )
	{
		SqlCommand  aCommand = new SqlCommand ( "RegionSelect" , conn ) ;

		aCommand.CommandType = CommandType.StoredProcedure ;
		aCommand.UpdatedRowSource = UpdateRowSource.None ;

		return aCommand ;
	}

	/// <summary>
	/// Create a command that will update a region record
	/// </summary>
	/// <param name="conn">The database connection</param>
	/// <returns>A SqlCommand</returns>
	private static SqlCommand GenerateUpdateCommand ( SqlConnection conn )
	{
		SqlCommand  aCommand = new SqlCommand ( "RegionUpdate" , conn ) ;

		aCommand.CommandType = CommandType.StoredProcedure ;
		aCommand.Parameters.Add ( new SqlParameter ( "@RegionID" , SqlDbType.Int , 0 , "RegionID" ) ) ;
		aCommand.Parameters.Add ( new SqlParameter ( "@RegionDescription" , SqlDbType.NChar , 50 , "RegionDescription" ) ) ;
		aCommand.UpdatedRowSource = UpdateRowSource.None ;

		return aCommand ;
	}

	/// <summary>
	/// Create a command that will insert a region record
	/// </summary>
	/// <param name="conn">The database connection</param>
	/// <returns>A SqlCommand</returns>
	private static SqlCommand GenerateInsertCommand ( SqlConnection conn )
	{
		SqlCommand  aCommand = new SqlCommand ( "RegionInsert" , conn ) ;

		aCommand.CommandType = CommandType.StoredProcedure ;
		aCommand.Parameters.Add ( new SqlParameter ( "@RegionDescription" , SqlDbType.NChar , 50 , "RegionDescription" ) ) ;
		aCommand.Parameters.Add ( new SqlParameter ( "@RegionID" , SqlDbType.Int, 0 , ParameterDirection.Output ,
			false , 0 , 0 , "RegionID" , DataRowVersion.Default , null ) ) ;
		aCommand.UpdatedRowSource = UpdateRowSource.OutputParameters ;

		return aCommand ;
	}

	/// <summary>
	/// Create a command that will delete a region record
	/// </summary>
	/// <param name="conn">The database connection</param>
	/// <returns>A SqlCommand</returns>
	private static SqlCommand GenerateDeleteCommand ( SqlConnection conn )
	{
		SqlCommand  aCommand = new SqlCommand ( "RegionDelete" , conn ) ;

		aCommand.CommandType = CommandType.StoredProcedure ;
		aCommand.Parameters.Add ( new SqlParameter ( "@RegionID" , SqlDbType.Int , 0 , "RegionID" ) ) ;
		aCommand.UpdatedRowSource = UpdateRowSource.None ;

		return aCommand ;
	}

	/// <summary>
	/// Create the Region DataTable
	/// </summary>
	/// <param name="ds">The dataset within which to create the data table</param>
	private static void CreateTable ( DataSet ds )
	{
		DataTable	dt = new DataTable ( "Region" ) ;

		DataColumn	regionID = new DataColumn ( "RegionID" , typeof ( int ) ) ;
		regionID.AllowDBNull = false ;
		regionID.AutoIncrement = true ;
		regionID.AutoIncrementSeed = 1 ;

		DataColumn	regionDescription = new DataColumn ( "RegionDescription" , typeof ( string ) ) ;
		regionDescription.AllowDBNull = false ;

		dt.Columns.Add ( regionID ) ;
		dt.Columns.Add ( regionDescription ) ;

		ds.Tables.Add ( dt ) ;
	}

}