如何使用数据库中的值填充数据表 [英] how can I populate data table with values from a database

问题描述

我想用从数据库中获取的值填充数据表。我想将Select条件与从文本框中获取的值一起使用。我已经在C＃中编写了以下代码，请告诉我这是否是正确的方法。它显示有关连接字符串的异常..但我想知道我的方法是否正确..请发表评论。

I wanted to populate data table with the value taken from the database. I want to use Select condition with the values taken from textbox.. I have written the following code in C#, please tell me whether it is a right approach. It is showing exception about connection string.. but I wanted to know whether my approach is correct or not.. please do comment.

public partial class searchsale : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        try
        {

            SqlConnection conn = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\rdb.mdf;Integrated Security=True;User Instance=True");

            conn.Open();
            string scriptname = TextBox1.Text;
            string accnum = TextBox2.Text;
            string sql = @"select scriptname,accnum,Quantity,price from transac where scriptname = @sn, accnum = @an and transactio = 'Sell'";
            SqlCommand cmd = new SqlCommand();
            cmd.CommandType = CommandType.Text;
            cmd.CommandText = sql;
            cmd.Parameters.AddWithValue("@an", accnum);
            cmd.Parameters.AddWithValue("@sn", scriptname);
            SqlDataReader dr = cmd.ExecuteReader();
            DataTable dt = GetDataTable(sql);
        }
        catch (Exception ex)
        {
            Response.Write("error" + ex.ToString());
        }

    }
    private DataTable GetDataTable (string sql)
    {
        DataTable dt = new DataTable();
        using (SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ToString()))
        {
            SqlDataAdapter da = new SqlDataAdapter(sql, conn);
            da.Fill(dt);
        }
        return dt;
    }
}

推荐答案

代码错误是因为您尚未设置命令的连接属性。

The error with your code is because you have not set the connection property of your command .

对于使用数据表，最简单的方法是使用：

and for using data table the most simple way is using :

try
{
    var connection = @"your connection string";
    //your command
    var command = "your command";
    var dataAdapter = new System.Data.SqlClient.SqlDataAdapter(command, connection);
    var dataTable = new DataTable();

    //Get data
    dataAdapter.Fill(dataTable);
}
catch (System.Data.SqlClient.SqlException sqlEx)
{
    //Use sqlEx.Number to hanlde excception more specific
    //for example if sqlEx.Number -1 => Could Not Connect to Server.
}
catch (Exception ex)
{
}

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