this.cbbUserlist.DataSource = dtForList;
this.cbbUserlist.ValueMember = "ID";
this.cbbUserlist.DisplayMember = "名称";
dtForList是你从数据库中读取出的表
string userid = this.cbbUserlist.SelectedValue.ToString();这个是获取ID的代码,你转换成int型就可以了
string sql = "SELECT [ID], [名称] FROM 表一";
DataSet ds = new DataSet();
//查询的部分省略了
comboBox1.DataSource = ds;
comboBox1.ValueMember = "ID";
comboBox1.DisplayMember = "姓名";