C# 如何从下拉列表框中获取值
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How to get value from drop down list box
提问by user1954418
What I want is to get the value from the selected item in the drop down list, and use it to query (select table) in a button click event.
我想要的是从下拉列表中的所选项目中获取值，并在按钮单击事件中使用它来查询（选择表）。
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
if (DropDownList1.SelectedIndex == 1)
{
using (SqlConnection con = new SqlConnection(DBcon))
{
SqlCommand sqlCommand = new SqlCommand("Select * from tbl_WinApps_FileHeader");
sqlCommand.Connection = con;
SqlDataReader read = sqlCommand.ExecuteReader();
GridView1.DataSource = read;
GridView1.DataBind();
}
}
}
<asp:DropDownList ID="DropDownList1" runat="server"
onselectedindexchanged="DropDownList1_SelectedIndexChanged">
<asp:ListItem>ER00 - File Header</asp:ListItem>
<asp:ListItem>ER01 - Expense Report Trans</asp:ListItem>
<asp:ListItem>ER02 - Expense Report Item Trans</asp:ListItem>
<asp:ListItem>ER03 - Expense Report Item Tax Trans</asp:ListItem>
<asp:ListItem>ER04 - Expense Report Item</asp:ListItem>
</asp:DropDownList>
回答by Adil
You can use SelectedValueproperty of DropDownList. To see how to add parameter to the select query in where clause see this post.
您可以使用SelectedValue属性DropDownList。要了解如何向 where 子句中的选择查询添加参数，请参阅此帖子。
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
string sel = DropDownList1.SelectedValue.ToString();
// if (DropDownList1.SelectedIndex == 1)
// {
using (SqlConnection con = new SqlConnection(DBcon))
{
SqlCommand sqlCommand = new SqlCommand("Select * from tbl_WinApps_FileHeader");
sqlCommand.Connection = con;
SqlDataReader read = sqlCommand.ExecuteReader();
GridView1.DataSource = read;
GridView1.DataBind();
}
//}
}
回答by Soner G?nül
You should use SelectedValueproperty.
你应该使用SelectedValue财产。
Gets the value of the selected item in the list control, or selects the item in the list control that contains the specified value.
获取列表控件中选定项的值，或选择列表控件中包含指定值的项。
DropDownList1.SelectedValue.ToString();
Like;
喜欢;
string val = DropDownList1.SelectedValue.ToString();
using (SqlConnection con = new SqlConnection(DBcon))
{
SqlCommand sqlCommand = new SqlCommand("Select * from tbl_WinApps_FileHeader");
sqlCommand.Connection = con;
SqlDataReader read = sqlCommand.ExecuteReader();
GridView1.DataSource = read;
GridView1.DataBind();
}
If you want to use it as a parameter in your SqlCommand, you can use it like;
如果你想在你的 中使用它作为参数SqlCommand，你可以像这样使用它；
SqlCommand sqlCommand = new SqlCommand("Select * from tbl_WinApps_FileHeader WHERE val = @val");
sqlCommand.Parameters.AddWithVAlue("@val", val);
sqlCommand.Connection = con;
SqlDataReader read = sqlCommand.ExecuteReader();
回答by Freelancer
DropDownList1.SelectedValue.ToString();
Or
或者
DropDownList1.Text;
Or
或者
DropDownList1.SelectedValue.ToString();
