当我从下拉列表中选择时，如何从表中获取ID [英] How Do I Get Id From A Table When I Make Selection From Dropdownlist

问题描述

我在ajax modalpopupExtender中有一个下拉列表。我从表中填写下拉列表然后我想在下拉列表中获取所选项目的相应ID？



##我试过这个



{

i have a dropdownlist in ajax modalpopupExtender. i fill the dropdown from a table then i am trying to get the respective id of selected item in dropdownlist??

## i have try this one

{

string select =从表格中选择Id，其中colName =' msgstr+ ddlAddDistrict.SelectedItem.Text +';
;

sda.Fill（dt）;

if（dt.Rows.Count> 0）

{

int id = int.Parse（dt.Rows [0] [0] .ToString（））;

Response.Write（< script> alert（'+ id +' ）< / script>）;

}

}

##我也试过这一个

string id = ddlAddDistrict.DataValueField;



一旦尝试过这个

string select = "select Id from table where colName='" + ddlAddDistrict.SelectedItem.Text + "'";
SqlDataAdapter sda = new SqlDataAdapter(select, DatabaseConnection.CreateConnection());
DataTable dt = new DataTable();
sda.Fill(dt);
if (dt.Rows.Count > 0)
{
int id = int.Parse(dt.Rows[0][0].ToString());
Response.Write("<script>alert('" + id + "')</script>");
}
}
## i also tried this one
string id = ddlAddDistrict.DataValueField;

once tried this one

string MyQuery = string.Format("select Id from tableName where colName='{0}'", dropdownlsit.SelectedItem.Text);
        SqlConnection con = DatabaseConnection.CreateConnection();
        SqlCommand cmd = new SqlCommand(MyQuery, con);
        string MyId;
        MyId = cmd.ExecuteScalar() as string;

推荐答案

感谢所有人。我已经按照以下方式解决了我的问题



当我在设置下拉列表DataVAlueField属性时填写下拉列表。然后在代码中我没有正确访问





public void FillDropdownlist（）{

string select = 从表名中选择col1，col2;

DataTable dt = SelectData（select）;

if（dt.rows.count> 0）{

ddlAddDistrict.DataSource = dt;



ddlAddDistrict.DataTextField =col1;

ddlAddDistrict.DataValueField =id;

ddlAddDistrict.DataBind（）;

}



}

后来我检索这样的id



string q =从tablename中选择id，其中col1 ='+ ddlAddDistrict.SelectedValue +';



sqlcommand cmd = new sqlcommand（q，connect（））;



string id = cmd.ExecuteScalar（）。tostring（）;



谢谢你

al0t of thanks to you all people. i have fix my problem in the following way

when i have filled the dropdownlist at the time i used to set the dropdownlist DataVAlueField property. then in the code i did not accessed correctly


public void FillDropdownlist(){
string select = "select col1, col2 from tablename";
DataTable dt = SelectData(select);
if(dt.rows.count > 0){
ddlAddDistrict.DataSource = dt;

ddlAddDistrict.DataTextField = "col1";
ddlAddDistrict.DataValueField = "id";
ddlAddDistrict.DataBind();
}

}
later i retrieved the id in this way

string q = "select id from tablename where col1='"+ddlAddDistrict.SelectedValue+"'";

sqlcommand cmd = new sqlcommand(q, connect());

string id= cmd.ExecuteScalar().tostring();

thank u

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