Populating ComboBox from SQL in C# -

i trying populate combobox sql when assign value member it, gives me following error

cannot explicitly convert int string 

could me understand , correct mistake?

 void fillcombo()     {          string query_select = "select * department";          datatable dt = dataaccess.selectdata(query_select);          sqldatareader dr = dataaccess.selectdatareader(query_select);          while (dr.read())             {                 string dpt_name = dr.getstring(1);                 int dpt_id = (int)dr.getvalue(0);                 combobox1.datasource = dt;                 combobox1.valuemember = dpt_id; // error here                 combobox1.displaymember = dpt_name;              }     } 

you must assign name of column in datasource (datatable) valuemenmber , displaymember string, , don't need use while loop, :

void fillcombo() {     string query_select = "select * department";     datatable dt = dataaccess.selectdata(query_select);     combobox1.datasource = dt;     combobox1.valuemember = "columnname_departmentid";     combobox1.displaymember = "columnname_departmentname"; }