从SQL查询到文本框获取数据

问题描述

通过在页面初始化关闭引黄联接，然后重新打开在DROPDOWNLIST固定它。

我搜索一个回答这个问题，但没有任何运气。

我想从选定的DropDownList项数据到一个文本框。我一直没有任何成功执行该SQL查询。

下面是我的code：

 公共部分类EditContact：System.Web.UI.Page
{
    SqlConnection的连接=新的SqlConnection（SqlConnection的）;
    保护无效的Page_Load（对象发件人，EventArgs的发送）
    {    }
    保护无效Page_Init（对象发件人，EventArgs的发送）
    {
        connection.Open（）;
        的SqlCommand SqlCommandDD =新的SqlCommand（SELECT名字+''+姓氏AS文本字段，CONTACT_ID，电子邮件，******中国，CompanyID FROM ContactPerson）;
        SqlCommandDD.Connection =连接;        DropDownList2.DataSource = SqlCommandDD.ExecuteReader（）;
        DropDownList2.DataValueField =CONTACT_ID;
        DropDownList2.DataTextField =文本字段;
        DropDownList2.DataBind（）;    }    保护无效DropDownList2_SelectedIndexChanged（对象发件人，EventArgs的发送）
    {
        字符串fNameTemp = DropDownList2.SelectedValue;
        字符串的SQLQuery =（选择firstname和ContactPerson WHERE（CONTACT_ID =+ fNameTemp +））;        的SqlCommand命令=新的SqlCommand（sqlquery的，连接）;        SqlDataReader的SDR = Command.ExecuteReader却（）;        fNameTextBox.Text = sdr.ToString（）;    }
}
 

解决方案

在的ExecuteReader返回复杂/非标量值。使用方法，而不是

 的SqlCommand命令=新的SqlCommand（sqlquery的，连接）;
fNameTextBox.Text = command.ExecuteScalar（）的ToString（）。
 

Fixed it by closing the connetion at page init and then reopen at Dropdownlist.

I've searched for an answer to this question but without any luck.

I want to get data from a selected dropdownlist item to a textbox. I've been trying to execute this sql query without any success.

Here's my code:

    public partial class EditContact : System.Web.UI.Page
{
    SqlConnection connection = new SqlConnection("SqlConnection");
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void Page_Init(object sender, EventArgs e)
    {
        connection.Open();
        SqlCommand SqlCommandDD = new SqlCommand("SELECT FirstName + ' ' + LastName AS 'TextField', Contact_ID, Email, PhoneNumber, CompanyID FROM ContactPerson");
        SqlCommandDD.Connection = connection;

        DropDownList2.DataSource = SqlCommandDD.ExecuteReader();
        DropDownList2.DataValueField = "Contact_ID";
        DropDownList2.DataTextField = "TextField";
        DropDownList2.DataBind();

    }

    protected void DropDownList2_SelectedIndexChanged(object sender, EventArgs e)
    {
        string fNameTemp = DropDownList2.SelectedValue;


        string sqlquery = ("SELECT FirstName FROM ContactPerson WHERE (Contact_ID = " + fNameTemp + ")");

        SqlCommand command = new SqlCommand(sqlquery, connection);

        SqlDataReader sdr = command.ExecuteReader();

        fNameTextBox.Text = sdr.ToString();

    }


}

解决方案

The "ExecuteReader" returns complex/non-scalar value. Use the "ExecuteScalar" method instead:

SqlCommand command = new SqlCommand(sqlquery, connection);
fNameTextBox.Text = command.ExecuteScalar().ToString();

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