gradem.cs

精通网络应用系统开发 光盘 该书是人民邮电出版社出版的

using System;
using System.Data;
using System.Configuration;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Data.Linq;
using System.Collections.Generic;

/// <summary>
/// Summary description for GradeM
/// </summary>
public class GradeM
{
	public GradeM()
	{
	}
    /// <summary>
    ///  获取所有的年级
    /// </summary>
    /// <returns>年级集合</returns>
    public Table<Grade> GetGrades()
    {
        //创建数据上下文
        DataClassesDataContext db = new DataClassesDataContext();
        Table<Grade> grades;
        try
        {
            //获取数据集合
            grades = db.Grades;
        }
        catch (Exception ex)
        {
            ///抛出执行数据库异常
            throw new Exception(ex.Message, ex);
        }

        ///返回从数据库获取的结果
        return (grades);
    }
    /// <summary>
    /// 获取指定ID的年级
    /// </summary>
    /// <param name="nGradeID">年级ID</param>
    /// <returns>一个年级对象</returns>
    public Grade GetSingleGrade(int nGradeID)
    {
        DataClassesDataContext db = new DataClassesDataContext();
        Grade grade;
        try
        {
            //根据条件获取年级对象
            grade = db.Grades.Where(g => g.GradeID == nGradeID).First();
        }
        catch (Exception ex)
        {
            ///抛出执行数据库异常
            throw new Exception(ex.Message, ex);
        }

        ///返回从数据库获取的结果
        return (grade);
    }
    /// <summary>
    /// 添加一个新的年级
    /// </summary>
    /// <param name="sDesn">年级名称</param>
    /// <param name="nYearDate">时间</param>
    /// <param name="nSemester">包含的学期</param>
    /// <returns></returns>
    public void AddGrade(string sDesn, int nYearDate, int nSemester)
    {
        DataClassesDataContext db = new DataClassesDataContext();
        try
        {
            //创建新年级对象
            Grade grade = new Grade { Desn = sDesn, YearDate = nYearDate, Semester = nSemester };
            //将新对象添加到上下文和数据库
            db.Grades.InsertOnSubmit(grade);
            db.SubmitChanges();
        }
        catch (Exception ex)
        {
            ///抛出执行数据库异常
            throw new Exception(ex.Message, ex);
        }
    }
    /// <summary>
    /// 更新指定的年级信息
    /// </summary>
    /// <param name="nGradeID">年级ID</param>
    /// <param name="sDesn">年级名称</param>
    /// <param name="nYearDate">年级的时间</param>
    /// <param name="nSemester">包含的学期</param>
    public void UpdateGrade(int nGradeID, string sDesn, int nYearDate, int nSemester)
    {
        DataClassesDataContext db = new DataClassesDataContext();
        try
        {
            //找到指定的年级对象
            Grade grade = db.Grades.Where(g => g.GradeID == nGradeID).First();
            //更改年级的信息
            grade.Desn = sDesn;
            grade.YearDate = nYearDate;
            grade.Semester = nSemester;
            //提交数据到上下文和数据库
            db.SubmitChanges();
        }
        catch (Exception ex)
        {
            ///抛出执行数据库异常
            throw new Exception(ex.Message, ex);
        }
    }
    /// <summary>
    /// 删除指定的年级
    /// </summary>
    /// <param name="nGradeID">年级ID</param>
    public void DeleteGrade(int nGradeID)
    {
        DataClassesDataContext db = new DataClassesDataContext();

        try
        {
            //找到指定的年级对象
            Grade grade = db.Grades.Where(g => g.GradeID == nGradeID).First();
            //从数据库和上下文中删除
            db.Grades.DeleteOnSubmit(grade);
            db.SubmitChanges();
        }
        catch (Exception ex)
        {
            ///抛出执行数据库异常
            throw new Exception(ex.Message, ex);
        }
    }
}