sampleobject.cs

东软内部材料（四）asp等相关的教学案例

using System;
using System.Data;
using System.Data.SqlClient;


namespace BusObjectCS {

public class IBAProducts {

  private string m_DSN;

  public  IBAProducts () {
    m_DSN="";
  }

  public  IBAProducts (string DSN) {
    m_DSN = DSN;
  }

  public string DatabaseConnection {
    set { m_DSN = value; }
    get { return m_DSN; }
  }

  public DataSet GetProducts (string productType) {
    if (m_DSN == "")
    {
       throw new ArgumentNullException("DatabaseConnection", "No value for the "
                                                + "database connection string");
    }
    SqlConnection myConnection = new SqlConnection(m_DSN);
    SqlDataAdapter sqlAdapter1 = new SqlDataAdapter("SELECT * FROM Products "
                      + "WHERE ProductType='"+productType+"'", myConnection);

    DataSet products = new DataSet();
    sqlAdapter1.Fill(products, "products");

    return products;
  }

  public DataSet GetProductTypes () {

    if (m_DSN == "")
    {
       throw new ArgumentNullException("DatabaseConnection", "No value for the "
                                                + "database connection string");
    }
    SqlConnection dbConnection = new SqlConnection(m_DSN);
    dbConnection.Open();

    SqlDataAdapter sqlAdapter1 = new SqlDataAdapter("SELECT DISTINCT ProductType "
                                                 + "FROM Products", dbConnection);

    DataSet types = new DataSet();
    sqlAdapter1.Fill(types, "ProdTypes");

    return types;
  }

  public Double AveragePrice (string productType) {
    if (m_DSN == "")
    {
      throw new ArgumentNullException("DatabaseConnection",
                                      "No value for the database connection string");
    }
    SqlConnection dbConnection = new SqlConnection(m_DSN);
    dbConnection.Open();

    SqlDataAdapter sqlAdapter1 = new SqlDataAdapter(
    "SELECT AVG(UnitPrice) AS AveragePrice FROM Products WHERE "
                              + "ProductType='" + productType + "'", dbConnection);

    DataSet AvgPrice = new DataSet();
    sqlAdapter1.Fill(AvgPrice, "AveragePrice");


    DataTable priceTable;
    priceTable = AvgPrice.Tables["AveragePrice"];
    if (priceTable.Rows.Count > 0)
    {
      return (Double)priceTable.Rows[0]["AveragePrice"];
    }
    else
      return 0;
    }
  }
}