sql连接及操作

               string userid = string.Empty;
               string roseid = string.Empty;
               SqlConnection connect = new SqlConnection("server=192.168.0.1;uid=sa;pwd=sa;database=data1");
                connect.Open();
                //获取userid
                SqlCommand ComUserid = new SqlCommand("select userid from aspnet_Users where username='" + name + "'", connect);
                SqlDataReader dr = ComUserid.ExecuteReader();
                if (dr.Read())
                {
                    userid = dr["userid"].ToString();
                }
                dr.Close();
                dr.Dispose();
                ComUserid.Dispose();
                SqlCommand ComDelete = new SqlCommand("delete from [aspnet_UsersInRoles] where userid = '" + userid + "'", connect);
                ComDelete.ExecuteNonQuery();//删除aspnet_UsersInRoles表中所有此用户得所有角色.
                ComDelete.Dispose();
             try
            {
                //获取选择得rolesid,更新角色.
                for (int i = 0; i < CheckBoxList1.Items.Count; i++)
                {
                    if (CheckBoxList1.Items[i].Selected)
                    {
                        string rosename = CheckBoxList1.Items[i].Text.ToString();
                       SqlCommand ComRosid = new SqlCommand("select roleid from aspnet_Roles where rolename='" + rosename + "'", connect);
                        SqlDataReader drRid = ComRosid.ExecuteReader();
                        if (drRid.Read())
                        {
                            roseid = drRid["roleid"].ToString();
                        }
                        drRid.Close();
                        drRid.Dispose();
                        ComRosid.Dispose();
                        string aa = "insert into [aspnet_UsersInRoles] [userid],[roleid] values('" + userid + "','" + roseid + "')";
                        SqlCommand cominsert = new SqlCommand("insert into [aspnet_UsersInRoles] ([userid],[roleid]) values('" + userid + "','" + roseid + "')", connect);
                        cominsert.ExecuteNonQuery();
                        cominsert.Dispose();
                     
                    }
                }
                connect.Close();//关闭数据库.
                connect.Dispose();
            }
            catch (Exception ex)
            {
                throw ex;
            }