ado.net 学习 06 DataSet,DataTable提供一个有用的方法Select()

1.DataTable提供一个有用的方法Select()，它可以使用SQL表达式查询某行，Select()方法使用的表达式和select语句的Where子句的作用一样，其依据是DataTable中已经存在内在数据。

　　DataRow[] matchRows = ds.Tables["Products"].Select("discontinued=1");

 

    protected void Page_Load(object sender, EventArgs e)
    {
        // Create the Connection, DataAdapter, and DataSet.
        string connectionString = WebConfigurationManager.ConnectionStrings["Northwind"].ConnectionString;
        SqlConnection con = new SqlConnection(connectionString);

        string sqlProd = "SELECT ProductName, CategoryID,discontinued FROM Products";

        SqlDataAdapter da = new SqlDataAdapter(sqlProd, con);
        DataSet ds = new DataSet();

        try
        {
            con.Open();
            // Fill the DataSet with the Products table.
            da.Fill(ds, "Products");
        }
        finally
        {
            con.Close();
        }

        StringBuilder htmlStr = new StringBuilder("");

        DataRow[] matchRows = ds.Tables["Products"].Select("discontinued=1");

        foreach (DataRow childRow in matchRows)
        {
            htmlStr.Append("<li>");
            htmlStr.Append(childRow["ProductName"].ToString());
            htmlStr.Append("</li>");
        }
        htmlStr.Append("</ul>");

        // Show the generated HTML code.
        HtmlContent.Text = htmlStr.ToString();
    }

运行结果：

对比