Table structure: Description of Column name data type
ID int Child add primary key
userlevel String Department name
Method One: Insert a blank row into the DataTable, and then bind DropDownList to the DataTable
Add a blank line to the first row of a DataTable
DataRow dr = ds. Tables[0]. NewRow ();
dr["name"] = "";
dr["username"] = "";
Ds. Tables[0]. Rows.insertat (DR, 0);
Binding
This.ddlUsername.DataSource = ds. Tables[0]. DefaultView;
This.ddlUsername.DataTextField = "name";
This.ddlUsername.DataValueField = "username";
This.ddlUsername.DataBind ();
Method Two: Bind the DropDownList directly to the DataTable, and then add a blank line to the DataTable.
/***************************************
Binding
This.ddlUsername.DataSource = ds. Tables[0]. DefaultView;
This.ddlUsername.DataTextField = "name";
This.ddlUsername.DataValueField = "username";
This.ddlUsername.DataBind ();
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This allows you to dropdownlist the desired value of the binding, and the first line in the DropDownList is blank.