c# comboBox绑定数据后会默认显示第一个值

一直困扰我很久的问题

当comboBox绑定数据源后，会显示第一个值

例如

         cboDept.DataSource = datatable
         cboDept.ValueMember = "字段名";
         cboDept.DisplayMember = "字段名";
         cboDept.Text = "";

但cboDept会显示一个值，而不是空白，可能是触发了combobox的selectIndexchange事件，解决办法将SelectIndex设为-1

 

         cboDept.DataSource = datatable
         cboDept.ValueMember = "字段名";
         cboDept.DisplayMember = "字段名";
         cboDept.SelectIndex=-1;