Winform查询

 用Winform来查询筛选学生信息，首先在后台写好查询的代码，然后在到前台那里去调用。具体的方法如下：

 /// <summary>

        /// 根据班级、学号、考好查询学员信息

        /// </summary>

        /// <param name="className"></param>

        /// <returns></returns>

        public List<StudentExt> GetStudentByClass(string className)

        {

            string sql = "select StudentName,StudentId,Gender,Birthday,ClassName from Students";

            sql += " inner join StudentClass on Students.ClassId=StudentClass.ClassId";

            sql += " where ClassName='{0}'";

            sql = string.Format(sql, className);

            SqlDataReader objReader = SQLHelper.GetReader(sql);

            List<StudentExt> list = new List<StudentExt>();

            while (objReader.Read())

            {

                list.Add(new StudentExt()

                {

                    StudentId = Convert.ToInt32(objReader["StudentId"]),

                    StudentName = objReader["StudentName"].ToString(),

                    Gender = objReader["Gender"].ToString(),

                    Birthday = Convert.ToDateTime(objReader["Birthday"]),

                    ClassName = objReader["ClassName"].ToString()                 

                });

            }

            objReader.Close();

            return list;

        }

 /// <summary>

        /// 根据学号查询

        /// </summary>

        /// <param name="sender"></param>

        /// <param name="e"></param>

        private void btnQueryById_Click(object sender, EventArgs e)

        {

            if (this.txtStudentId.Text.Trim().Length == 0)

            {

                MessageBox.Show("请输入学号！", "提示信息");

                this.txtStudentId.Focus();

                return;

            }

            //进一步验证学号必须是数字（请使用正则表达式...）

 

            //执行查询

            StudentExt objStudent = objStuService.GetStudentById(this.txtStudentId.Text.Trim());

            if (objStudent == null)

            {

                MessageBox.Show("学员信息不存在！", "提示信息");

                this.txtStudentId.Focus();

            }

            else

            {

                //在学员详细信息窗体显示

                FrmStudentInfo objFrmStuInfo = new FrmStudentInfo(objStudent);

                objFrmStuInfo.Show();

            }

        }

结果如下图：