C#深入.NET平台的软件系统分层开发

今天我们来讲讲分层开发，你从标题能不能简单的认识一下什么是分层呢？

不懂也没关系，接下来我来给你讲讲。

第一章软件系统的分层开发

（1）其实分层模式可以这样定义：将解决方案中功能不同的模块分到不同的项目中实现，每一层中的组件应保持内聚性，每一层都应该与它下面的各层保持松耦合。

分层模式是最常见的一种架构模式，甚至可以说分层模式是很多架构模式的基础。

数据访问层：

这一层处于最底层，负责与数据库的交互，也成为DAL（Data Access Layer）

表示层：

这一层直接与用户打交道，负责显示或者获取数据，也称为UI（User Interface Layer）

（2）.NET程序集是任何.NET Framework应用程序的基本构造块。程序集由描述它的程序集清单（包含版本号，程序集名称等），类型元数据，MSIL代码和资源组成，

这些部分都分布在一个文件中。

程序集主要包括以下两类：

（1）可执行文件，即.exe文件（2）类库文件，即.dll文件

（3）程序集，解决方案，项目和命名空间的关系如下：

（1）一个解决方案可以由一个或者多个项目组成，这些项目可以是Windows应用程序，类库等。

（2）一个程序集可以包含多个命名空间，程序集默认的命名空间名称就是程序集的名称。

（3）命名空间是组织C#程序的一种逻辑架构，一个命名空间可以有多个类。

（4）分层开发的优点：

（1）代码的复用（2）分离开发人员的关注（3）无损提换（4）降低了系统间的依赖

（5）异常处理

常见的异常类型:

System.Exception :这个类提供系统异常和应用程序异常之间的区别

System.SQLException :当SQL Server返回警告或者错误时引发的异常

ArgumentNullException :当将空引用传递给不接受它作为有效参数的方法时引发的异常

FileNotFoundException :试图访问磁盘上不存在的文件失败时引发的异常

IOException :当出现I/O错误时，引发此异常

ApplicationException :在应用程序执行过程中检测到由应用程序定义的异常

异常类的常用属性：

Message :提供引起异常的详细信息

Source :表示导致异常发生的应用程序或者对象的名称

StackTrace :提供在栈堆上所调用方法的详细信息，并首先显示最近调用的方法

InnerException :对内部异常的引用，如果此异常基于前一个异常，则内部异常指最初发生的异常

（6）异常处理回顾

语法：

try-catchtry
{//可能引发异常的工作代码
}
catch(异常对象)
{//异常处理
}try-finallytry
{//可能引发异常的工作代码
}
finally
{//清理相关对象的代码
}try-catch-finallytry
{
//可能引发异常的工作代码
}
catch(异常对象)
{//异常处理
}
finally
{//清理相关对象的代码
}

上面的文字都是枯燥的，接下来用代码来演示一下：

  /// <summary>/// 数据访问层/// </summary>public  class StudentDAL{public  void AddStudent(){}public DataTable SelectStudent(){string str = "Data Source=.; initial catalog=MySchools;user id=sa;";string sql = "select * from student ";SqlConnection con = new SqlConnection(str);SqlDataAdapter da = new SqlDataAdapter(sql,con);DataSet ds = new DataSet();try{//int num = 0;//int result = 1 / num;da.Fill(ds, "stuInfo");return ds.Tables["stuInfo"];}catch (SqlException ex){throw new Exception("访问数据库失败" + ex.Message);}catch (DivideByZeroException ex){throw new Exception("除数不能为0" + ex.Message);}catch (Exception ex){throw new Exception("失败" + ex.Message);}}

 /// <summary>/// 数据访问层/// </summary>public class GradeDAL{public DataTable SelectGrade(){string str = "data source=.; initial catalog=MySchools; user id=sa;";string sql = "select * from Grade";SqlConnection con = new SqlConnection(str);SqlDataAdapter da = new SqlDataAdapter(sql,con);DataSet ds = new DataSet();da.Fill(ds,"gradeInfo");return ds.Tables["gradeInfo"];}}

 private void Form1_Load(object sender, EventArgs e){StudentDAL dal = new StudentDAL();GradeDAL grade = new GradeDAL();try{DataTable data = dal.SelectStudent();DataTable table = grade.SelectGrade();dgvList.DataSource = data;comboBox1.DataSource = grade.SelectGrade();comboBox1.DisplayMember = "GradeName";comboBox1.ValueMember = "GradeId";}catch (Exception ex){MessageBox.Show(ex.Message);}}

第二章 OOP典型应用：实体类

（1）实体类是业务对象的基础，它用面向对象的思想消除了关系数据与对象之间的差异

实体类:

/// <summary>/// 部门表/// </summary>public class Department{public int BId { get; set; }public int BName{ get; set; }}

 /// <summary>/// 员工表/// </summary>public class Employee{public int YId{ get; set; }public int YName{ get; set; }public int BId{ get; set; }public int ZId{ get; set; }}

 /// <summary>/// 任务内容表/// </summary>public class Task{public string Contents {get;set;}public int RId {get;set;}public int YId {get;set;}public DateTime Time {get;set;}public int Hours {get;set;}public string Type { get; set; }}

数据访问层：

public  class InfoAddDAL{public bool Add(string name){bool falg = false;string sql = "insert into ProgramInfo(pname) values('"+name+"')";int num=SQLHelper.ExecuteNonQuery(sql);if(num==1){falg= true;}return falg;}public DataTable SelectInfo(){List<string> list = new List<string>();try{   string sql = "select pname from ProgramInfo";DataTable table=SQLHelper.ExecuteDataTable(sql);         return table;}catch (SqlException ex){throw ex;}catch(Exception ex){throw ex;}  }public bool DeleteInfo(string name){bool falg = false;try{string sql = "delete ProgramInfo where pname='" + name + "'";int num=SQLHelper.ExecuteNonQuery(sql);if (num == 1){falg= true;}return falg;}catch (SqlException ex){throw ex;}catch(Exception ex){throw ex;}}public bool UpdateInfo(string name,string names){bool falg = false;       string sql = "Update  ProgramInfo set pname='"+name+"'where pname='"+names+"'";int num=SQLHelper.ExecuteNonQuery(sql);if(num==1){falg= true;}return falg;}}

接下来是一个辅助类，因为以后要经常用，有能力的自己写一个工具吧！

 public static  class SQLHelper{//用静态的方法调用的时候不用创建SQLHelper的实例//Execetenonquery// public static string Constr = "server=HAPPYPIG\\SQLMODEL;database=shooltest;uid=sa;pwd=6375196;";public static string Constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;public static int id;/// <summary>/// 执行NonQuery命令/// </summary>/// <param name="cmdTxt"></param>/// <param name="parames"></param>/// <returns></returns>public static int ExecuteNonQuery(string cmdTxt, params SqlParameter[] parames){return ExecuteNonQuery(cmdTxt, CommandType.Text, parames);}//可以使用存储过程的ExecuteNonquerypublic static int ExecuteNonQuery(string cmdTxt, CommandType cmdtype, params SqlParameter[] parames){//判断脚本是否为空 ，直接返回0if (string.IsNullOrEmpty(cmdTxt)){return 0;}using (SqlConnection con = new SqlConnection(Constr)){using (SqlCommand cmd = new SqlCommand(cmdTxt, con)){if (parames != null){cmd.CommandType = cmdtype;cmd.Parameters.AddRange(parames);}con.Open();return cmd.ExecuteNonQuery();}}}public static SqlDataReader ExecuteDataReader(string cmdTxt, params SqlParameter[] parames){return ExecuteDataReader(cmdTxt, CommandType.Text, parames);}//SQLDataReader存储过程方法public static SqlDataReader ExecuteDataReader(string cmdTxt, CommandType cmdtype, params SqlParameter[] parames){if (string.IsNullOrEmpty(cmdTxt)){return null;}SqlConnection con = new SqlConnection(Constr);using (SqlCommand cmd = new SqlCommand(cmdTxt, con)){cmd.CommandType = cmdtype;if (parames != null){cmd.Parameters.AddRange(parames);}con.Open();//把reader的行为加进来。当reader释放资源的时候，con也被一块关闭return cmd.ExecuteReader(System.Data.CommandBehavior.CloseConnection);}}public static DataTable ExecuteDataTable(string sql, params SqlParameter[] parames){return ExecuteDataTable(sql, CommandType.Text, parames);}//调用存储过程的类，关于(ExecuteDataTable)public static DataTable ExecuteDataTable(string sql, CommandType cmdType, params SqlParameter[] parames){if (string.IsNullOrEmpty(sql)){return null;}DataTable dt = new DataTable();using (SqlDataAdapter da = new SqlDataAdapter(sql, Constr)){da.SelectCommand.CommandType = cmdType;if (parames != null){da.SelectCommand.Parameters.AddRange(parames);}da.Fill(dt);return dt;}}/// <summary>/// ExecuteScalar/// </summary>/// <param name="cmdTxt">第一个参数，SQLServer语句</param>/// <param name="parames">第二个参数，传递0个或者多个参数</param>/// <returns></returns>public static object ExecuteScalar(string cmdTxt, params SqlParameter[] parames){return ExecuteScalar(cmdTxt, CommandType.Text, parames);}//可使用存储过程的ExecuteScalarpublic static object ExecuteScalar(string cmdTxt, CommandType cmdtype, params SqlParameter[] parames){if (string.IsNullOrEmpty(cmdTxt)){return null;}using (SqlConnection con = new SqlConnection(Constr)){using (SqlCommand cmd = new SqlCommand(cmdTxt, con)){cmd.CommandType = cmdtype;if (parames != null){cmd.Parameters.AddRange(parames);}con.Open();return   cmd.ExecuteScalar();}}}//调用存储过程的DBHelper类（关于ExeceutScalar,包含事务,只能处理Int类型，返回错误号）public static object ExecuteScalar(string cmdTxt, CommandType cmdtype,SqlTransaction sqltran, params SqlParameter[] parames){if (string.IsNullOrEmpty(cmdTxt)){return 0;}using (SqlConnection con = new SqlConnection(Constr)){int sum = 0;using (SqlCommand cmd = new SqlCommand(cmdTxt, con)){cmd.CommandType=cmdtype;if (parames != null){cmd.Parameters.AddRange(parames);}con.Open();sqltran = con.BeginTransaction();try{cmd.Transaction = sqltran;sum=Convert.ToInt32( cmd.ExecuteScalar());sqltran.Commit();}catch (SqlException ex){sqltran.Rollback();}return sum;}}}}

数据访问层：

 public class TaskDAL{//查询信息public DataTable Info(){string sql = "select Contents,YName,  Time, Hours, Type from Task,Employee where Task.YId=Employee.YId";DataTable table =SQLHelper.ExecuteDataTable(sql);return table;}public DataTable RSelectInfo(Task task){string sql = "select Contents,YName,  Time, Hours, Type from Task,Employee where Task.YId=Employee.YId and Contents='"+task.Contents+"'";DataTable table = SQLHelper.ExecuteDataTable(sql);return table;}//根据条件查询public DataTable SelectInfo(DateTime time1, DateTime time2){  string sql = "select Contents,YName,  Time, Hours, Type from Task,Employee where Time between'" + time1 + "' and '"+ time2 + "' and Task.YId=Employee.YId";DataTable table = SQLHelper.ExecuteDataTable(sql);return table;}//加载任务名称public DataTable RInfo(){string sql = "select Contents from Task ";DataTable table = SQLHelper.ExecuteDataTable(sql);return table;}}

在这里再引用一个App.config

<?xml version="1.0" encoding="utf-8" ?>
<configuration><connectionStrings><add name="constr" connectionString="data source=.; initial catalog=AddInfo; uid=sa;">  </add></connectionStrings><startup> <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5.2" /></startup>
</configuration>

窗体加载：

  private void FrmMain_Load(object sender, EventArgs e){txt02.Enabled = false;}private void btn01_Click(object sender, EventArgs e){InfoAddDAL info = new InfoAddDAL();if (txt02.Text==""){MessageBox.Show("请输入你要添加的文本");}else{try{bool falg = info.Add(txt02.Text);if (falg){DataTable table = info.SelectInfo();lb01.DataSource = table;lb01.DisplayMember = "pname";}txt02.Text = "";}catch (SqlException){MessageBox.Show("sql语句错误");}catch (Exception){MessageBox.Show("程序出错");}}}private void btn02_Click(object sender, EventArgs e){ InfoAddDAL info = new InfoAddDAL();string name = lb01.SelectedItem.ToString();bool falg = info.DeleteInfo(name);if (falg){DataTable table = info.SelectInfo();lb01.DataSource = table;lb01.DisplayMember = "pname";}}private void lb01_DoubleClick(object sender, EventArgs e){string name = lb01.SelectedItem.ToString();txt02.Text = name;}private void btn03_Click(object sender, EventArgs e){if(txt02.Text==""){MessageBox.Show("请选择要修改的文本");}else{string name = lb01.SelectedItem.ToString();InfoAddDAL info = new InfoAddDAL();bool falg = info.UpdateInfo(txt02.Text, name);if (falg){DataTable table = info.SelectInfo();lb01.DataSource = table;lb01.DisplayMember = "pname";}txt02.Text = "";}}private void btn04_Click(object sender, EventArgs e){txt02.Enabled = true;InfoAddDAL info = new InfoAddDAL();try{DataTable table = info.SelectInfo();lb01.DataSource = table;lb01.DisplayMember = "pname";}catch (SqlException){MessageBox.Show("sql语句错误");}catch (Exception){MessageBox.Show("程序出错");}}}

    TaskDAL DAL = new TaskDAL();DataTable table = null;private void btn01_Click(object sender, EventArgs e){DateTime time1 = dateTimePicker1.Value;DateTime time2 = dtp02.Value;if (cbo01.Text == ""){table = DAL.Info();}else if(time1.ToString() != "" && time2.ToString() != ""){table = DAL.SelectInfo(time1, time2);}else if(cbo01.Text!=""&& time1.ToString() != "" && time2.ToString() != ""){Task task = new Task();task.Contents = cbo01.SelectedText.ToString();table = DAL.RSelectInfo(task);} dgvList.DataSource = table;}private void FrmTwo_Load(object sender, EventArgs e){table= DAL.RInfo();cbo01.DisplayMember = "Contents";cbo01.DataSource = table;}

配置文件里保存的是应用程序运行所依赖的常量，这些常量可能会随着多种因素的变化而变化，所以将这些信息写在配置文件中，由程序来动态读取。
读取连接字符串的语法如下：

public static readonly string conString=ConfigurationManager.ConnectionStrings["MySchoolConnectionString"].ToString();

（2）const和readonly的区别

（1）readonly只能修饰类变量 const修饰成员变量和局部变量

（2）readonly在运行时赋值，const在编译时赋值

（3）const只能修饰值类型和特殊的引用类型 readonly可以修饰任何类型

第三章提高系统性能：从数据访问开始

（1）using语句

using的作用：（1）导入命名空间（2）释放实现了disposable接口的对象非托管资源

语法：

using(SqlConnection con=new SqlConnection(constr))

{

//数据库操作代码.......

}

（2）参数化命令（防止SQL注入攻击）

语法：

（1）使用参数名和参数类型进行设置public SqlParameter Add(string parameterName,SqlDbType slDbType);public SqlParameter Add(string parameterName,SqlDbType paraValue,int size);（2）使用SqlParameter对象进行填充public SqlParameter Add(SqlParameter  value);  //添加单个参数public void AddRange(SqlParameter[]  values);  //添加多个参数

（3）SqlParameter类的常用属性

DbType :获取或设置参数的DbTypeDirection :获取或设置一个值，该值表示参数是只可输入，是可输出，还是双向存储过程返回值参数IsNullable :获取或设置一个值，该值指示参数是否接受空值ParameterName :获取或设置SqlParameter的名称Size :获取或设置列中数据的最大值（以字节为单位）SqlDbType :获取或设置参数的SqlDbTypeValue ：获取或设置该参数的值

第四章业务的扩展：三层架构

（1）业务逻辑层BLL（Business Logic Layer）

实体类：

public class Grade{public int GradeId { get; set; }                        public string GradeName { get;set;}}

 public class Result{public int StudentNo { get; set; }public int SubjectId { get; set; }public int StudentResult { get; set; }public string ExamDate { get; set; }public int Id { get; set; }}

public class Student{public int StudentNo { get; set; }public string StudentName { get; set; }public string LoginPwd { get; set; }public int GradeId { get; set; }public string Gender { get; set; }public string Address { get; set; }public string Phone { get; set; }public DateTime Birthday { get; set; }public string Email { get; set; }public string IdentityId { get; set; }}

public class Subject{public int SubjectId { get; set; }public string SubjectName { get; set; }public int ClassHour { get; set; }public int GradeId { get; set; }}

数据访问层DAL：

 /// <summary>/// 班级表/// </summary>public  class GradeDAL{//加载班级信息public DataTable GradeInfo(){   string sql = "select * from Grade";DataTable table=SQLHelper.ExecuteDataTable(sql);return table;}}

  public class MyTool{/// <summary>/// DataSetToList/// </summary>/// <typeparam name="T">转换类型</typeparam>/// <param name="dataSet">数据源</param>/// <param name="tableIndex">需要转换表的索引</param>/// <returns></returns>public List<T> DataTableToList<T>(DataTable dt){//确认参数有效if (dt == null )return null;List<T> list = new List<T>();for (int i = 0; i < dt.Rows.Count; i++){//创建泛型对象T _t = Activator.CreateInstance<T>();//获取对象所有属性PropertyInfo[] propertyInfo = _t.GetType().GetProperties();for (int j = 0; j < dt.Columns.Count; j++){foreach (PropertyInfo info in propertyInfo){//属性名称和列名相同时赋值if (dt.Columns[j].ColumnName.ToUpper().Equals(info.Name.ToUpper())){if (dt.Rows[i][j] != DBNull.Value){info.SetValue(_t, dt.Rows[i][j], null);}else{info.SetValue(_t, null, null);}break;}}}list.Add(_t);}return list;}}

 /// <summary>///  成绩表/// </summary>public  class ResultDAL{//根据科目条件查询成绩public DataTable SelectResult(int subjectid){string sql = "select StudentName,SubjectName,StudentResult,ExamDate,student.studentno from student,subject,result where Subject.subjectid=result.subjectid and student.StudentNo=Result.StudentNo and result.subjectid="+subjectid+" ";DataTable table = SQLHelper.ExecuteDataTable(sql);return table;}//根据姓名查询成绩public DataTable SelectResult(string studentname){string sql = "select StudentName,SubjectName,StudentResult,ExamDate,student.studentno from student,subject,result where student.studentName like'%" + studentname + "%' and Subject.subjectid=result.subjectid and student.StudentNo=Result.StudentNo  ";DataTable table= SQLHelper.ExecuteDataTable(sql);return table;}//查询全部成绩public DataTable SelectResult(){string sql = "select StudentName,SubjectName,StudentResult,ExamDate,student.studentno from student,subject,result where Subject.subjectid=result.subjectid and student.StudentNo=Result.StudentNo  ";DataTable table = SQLHelper.ExecuteDataTable(sql);return table;}// 修改学生成绩public bool UpdateResult(Result result){bool flag = false;string sql = "update Result set StudentResult='" + result.StudentResult+ "',ExamDate='"+result.ExamDate+ "',SubjectId='"+result.SubjectId+"' where result.studentno="+result.StudentNo+"";int count= SQLHelper.ExecuteNonQuery(sql);if(count>0){flag = true;}return flag;}//添加学生成绩public bool AddResult(Result result){bool flag = false;string sql = "insert into result values(@studentno,@subjectid,@studentresult,@examdate)";SqlParameter[] para ={new SqlParameter("@studentno",result.StudentNo),new SqlParameter("@subjectid",result.SubjectId),new SqlParameter("@studentresult",result.StudentResult),new SqlParameter("@examdate",result.ExamDate)};int num=Convert.ToInt32(SQLHelper.ExecuteScalar(sql,para));if(num>0){flag = true;}return flag;}}

/// <summary>/// 学生表/// </summary>public class StudentDAL{//Login登录 public bool IsLogin(Student stu){#region 方式一：登录//bool flag = false;//string sql = "select count(1) from student where studentno=" + stu.StudentNo + " and Loginpwd='" + stu.LoginPwd + "'";//int count = Convert.ToInt32(SQLHelper.ExecuteScalar(sql));//if (count > 0)//{//    flag = true;//}//return flag;#endregion#region 方式二：登录bool flag = false;string sql = "select count(1) from student where studentno=@studentno and loginpwd=@pwd";SqlParameter[] para ={new SqlParameter("@studentno",stu.StudentNo),new SqlParameter("@pwd",stu.LoginPwd)};int count = Convert.ToInt32(SQLHelper.ExecuteScalar(sql, para));if (count > 0){flag = true;}return flag;#endregion}//根据条件学生信息// StudentNo, LoginPwd, StudentName, Gender, GradeId, Phone, Address, Birthday, Email,public List<Student> StudentInfo(int gradeid){#region 查询一List<Student> list = new List<Student>();string sql = "select StudentNo, LoginPwd, StudentName, Gender, GradeId, Phone, Address, Birthday, Email,IdentityId from student where GradeId=" + gradeid + "";SqlDataReader dr = SQLHelper.ExecuteDataReader(sql);if (dr.HasRows){while (dr.Read()){Student stu = new Student();stu.StudentNo = Convert.ToInt32(dr["StudentNo"]);stu.LoginPwd = dr["LoginPwd"].ToString();stu.StudentName = dr["StudentName"].ToString();stu.Gender = dr["Gender"].ToString();stu.GradeId = Convert.ToInt32(dr["GradeId"]);stu.Phone = dr["Phone"].ToString();stu.Address = dr["Address"].ToString();stu.Birthday = Convert.ToDateTime(dr["Birthday"]);stu.Email = dr["Email"].ToString();stu.IdentityId = dr["IdentityId"].ToString();list.Add(stu);}}dr.Close();return list;#endregion}public List<Student> StudentInfo(string name){#region 查询一List<Student> list = new List<Student>();string sql = "select StudentNo, LoginPwd, StudentName, Gender, GradeId, Phone, Address, Birthday, Email,IdentityId from student where StudentName=" + name + "";SqlDataReader dr = SQLHelper.ExecuteDataReader(sql);if (dr.HasRows){while (dr.Read()){Student stu = new Student();stu.StudentNo = Convert.ToInt32(dr["StudentNo"]);stu.LoginPwd = dr["LoginPwd"].ToString();stu.StudentName = dr["StudentName"].ToString();stu.Gender = dr["Gender"].ToString();stu.GradeId = Convert.ToInt32(dr["GradeId"]);stu.Phone = dr["Phone"].ToString();stu.Address = dr["Address"].ToString();stu.Birthday = Convert.ToDateTime(dr["Birthday"]);stu.Email = dr["Email"].ToString();stu.IdentityId = dr["IdentityId"].ToString();list.Add(stu);}}dr.Close();return list;#endregion}// 添加学生信息public int StudentAdd(Student stu){string sql = "insert into student values('" + stu.LoginPwd + "','" + stu.StudentName + "'," + stu.Gender + ",'" + stu.GradeId + "','" + stu.Phone + "','" + stu.Address + "','" + stu.Birthday + "','" + stu.Email + "','"+stu.IdentityId+"');select @@IDENTITY";int num = Convert.ToInt32(SQLHelper.ExecuteScalar(sql));return num;}//修改学生信息public bool UpdateInfo(Student stu){bool flag = false;string str = "data source=.; initial catalog=MySchool; uid=sa;";using (SqlConnection con = new SqlConnection(str)){SqlCommand com = con.CreateCommand();com.CommandText = "usp_Update";com.CommandType = CommandType.StoredProcedure;SqlParameter[] para ={new SqlParameter("@studentno",stu.StudentNo),new SqlParameter("@pwd",stu.LoginPwd),new SqlParameter("@name",stu.StudentName),new SqlParameter("@gender",stu.Gender),new SqlParameter("@gradeid",stu.GradeId),new SqlParameter("@phone",stu.Phone),new SqlParameter("@address",stu.Address),new SqlParameter("@birthday",stu.Birthday),new SqlParameter("@email",stu.Email),new SqlParameter("@identitycard",stu.IdentityId)};com.Parameters.AddRange(para);con.Open();int count = com.ExecuteNonQuery();if (count > 0){flag = true;}return flag;}}//查询全部学生信息public DataTable Student(){string sql = "select StudentNo, LoginPwd, StudentName, Gender, GradeName, Phone, Address, Birthday, Email,IdentityCard from student,grade where student.gradeid=grade.gradeid";DataTable table = SQLHelper.ExecuteDataTable(sql);return table;}//条件查询学生信息public DataTable Student(string name){string sql = "select StudentNo, LoginPwd, StudentName, Gender, GradeId, Phone, Address, Birthday, Email,IdentityCard from student,grade where gradename=@name and student.gradeid=grade.gradeid";SqlParameter para = new SqlParameter("@name", name);DataTable table = SQLHelper.ExecuteDataTable(sql, para);return table;}public DataTable SelectStudent(string gradename,string grader){string sql = "select StudentNo, LoginPwd, StudentName, Gender,student.Gradeid, Phone, Address, Birthday, Email,IdentityCard from student,grade where student.gradeid=grade.gradeid and gradename=@name and gender=@gender";SqlParameter[] para ={new SqlParameter("@name",gradename),new SqlParameter("@gender",grader)};DataTable table = SQLHelper.ExecuteDataTable(sql, para);return table;}public DataTable SelectStudent(string gradename){string sql = "select StudentNo, LoginPwd, StudentName, Gender,student.GradeId, Phone, Address, Birthday, Email,IdentityCard from student,grade where student.gradeid=grade.gradeid and gradename=@name";SqlParameter para = new SqlParameter("@name",gradename);DataTable table = SQLHelper.ExecuteDataTable(sql, para);return table;}}

 /// <summary>/// 科目表/// </summary>public class SubjectDAL{public DataTable SubjectInfo(){string sql = "select * from subject";DataTable table = SQLHelper.ExecuteDataTable(sql);return table;}public List<Subject> SubjectALL(int gradeid){string sql = "select * from subject where gradeid=@gradeid";SqlParameter para = new SqlParameter("@gradeid",gradeid);DataTable table = SQLHelper.ExecuteDataTable(sql,para);MyTool tool = new MyTool();List<Subject>  list=tool.DataTableToList<Subject>(table);return list;}}

业务逻辑层BLL：

 public class GradeBLL{GradeDAL dal = new GradeDAL();//加载年级信息public DataTable GradeInfo(){return dal.GradeInfo();}  }

public class ResultBLL{ResultDAL dal = new ResultDAL();public DataTable SelectResult(int subjectid){return dal.SelectResult(subjectid);}//条件查询public DataTable SelectResult(string studentname){return dal.SelectResult(studentname);}//查询全部public DataTable SelectResult(){return dal.SelectResult();}//修改成绩public bool UpdateResult(Result result){return dal.UpdateResult(result);}//添加学生成绩public bool AddResult(Result result){return dal.AddResult(result);}}

/// <summary>/// 逻辑层/// </summary>/// public class StudentBLL{StudentDAL dal = new StudentDAL();//登录public bool IsLogin(Student stu){//Common com = new Common();//string temp = com.GetMD5String(stu.LoginPwd);//stu.LoginPwd = temp;return dal.IsLogin(stu);}显示学生信息public List<Student> StudentInfo(int gradeid){return dal.StudentInfo(gradeid);}public List<Student> StudentInfo(string name){return dal.StudentInfo(name);}//增加学生信息public int StudentAdd(Student stu){//Common com = new Common();//string temp = com.GetMD5String(stu.LoginPwd);//stu.LoginPwd = temp;return dal.StudentAdd(stu);}public bool UpdateInfo(Student stu){return dal.UpdateInfo(stu);}public DataTable SelectStudent(string gradename,string grader ){return dal.SelectStudent(gradename, grader);}public DataTable SelectStudent(string gradename){return dal.SelectStudent(gradename);}public DataTable Student(){return dal.Student();}}

public class SubjectBLL{//加载科目信息SubjectDAL sdl = new SubjectDAL();public DataTable SubjectInfo(){return sdl.SubjectInfo();}public List<Subject> SubjectALL(int gradeid){return sdl.SubjectALL(gradeid);}}

表示层DAL：

登录窗体：

 public partial class FrmIsLogin : Form{public FrmIsLogin(){InitializeComponent();}StudentBLL bll = new StudentBLL();private void btn01_Click(object sender, EventArgs e){Student stu = new Student();stu.StudentNo = Convert.ToInt32(txt01.Text);stu.LoginPwd = txt02.Text;bool flag= bll.IsLogin(stu);if(flag){FrmMain mm = new FrmMain();Hide();mm.Show();// MessageBox.Show("Test");}}}

主窗体：

  public partial class FrmMain : Form{public FrmMain(){InitializeComponent();}private void toolStripMenuItem1_Click(object sender, EventArgs e){FrmAdd aa = new FrmAdd();aa.MdiParent = this;aa.Show();}private void toolStripMenuItem2_Click(object sender, EventArgs e){FrmInfo info = new FrmInfo();info.MdiParent = this;info.Show();}private void 添加学生成绩ToolStripMenuItem_Click(object sender, EventArgs e){FrmResult result = new FrmResult();result.MdiParent = this;result.Show();}private void 查询学生成绩ToolStripMenuItem_Click(object sender, EventArgs e){FrmSelectResult sr = new FrmSelectResult();sr.MdiParent = this;sr.Show();}private void 退出ToolStripMenuItem_Click(object sender, EventArgs e){Application.Exit();}}

添加和修改学生信息窗体：

    public partial class FrmAdd : Form{public FrmAdd(){InitializeComponent();}public int no;public string pwd;public string name;public string phone;public string address;public string gender;public string gradename;public string email;public string birthday;public string identitycard;StudentBLL bll = new StudentBLL();//添加学生private void btn01_Click(object sender, EventArgs e){//创建一个学生对象Student stu = new Student();stu.LoginPwd = txt02.Text;stu.StudentName = txt04.Text;stu.Gender = rb02.Checked ? "0" : "1";stu.Phone = txt05.Text;stu.Address = txt06.Text;stu.Birthday = Convert.ToDateTime(txt09.Text);stu.Email = txt07.Text;stu.GradeId = Convert.ToInt32(cbo01.SelectedValue);stu.IdentityId = txt08.Text;//把对象添加到数据表中if(txt01.Text!=""){stu.StudentNo = Convert.ToInt32(txt01.Text);bool flag = bll.UpdateInfo(stu);if (flag){MessageBox.Show("修改成功!");foreach (Control item in gb01.Controls){if (item is TextBox){item.Text = "";}}foreach (Control item in gb02.Controls){if (item is TextBox){item.Text = "";}rb01.Checked = true;cbo01.Text = "";}}}else{int result = bll.StudentAdd(stu);if (result>0){txt01.Text = result.ToString();MessageBox.Show("添加成功!");foreach (Control item in gb01.Controls){if (item is TextBox){item.Text = "";}}foreach (Control item in gb02.Controls){if (item is TextBox){item.Text = "";}rb01.Checked = true;cbo01.Text = "";}}}}GradeBLL gbl = new GradeBLL();//加载班级信息private void FrmAdd_Load(object sender, EventArgs e){cbo01.ValueMember = "GradeId";cbo01.DisplayMember = "gradeName";cbo01.DataSource= gbl.GradeInfo();if (this.Text == "添加学生信息"){btn01.Text = "添加";}else{btn01.Text = "修改";txt01.Text = no.ToString();txt02.Text = pwd;txt03.Text = pwd;txt04.Text = name;if (gender.Equals(0)){rb01.Checked = true;}else{rb02.Checked = true;}txt05.Text = phone;txt06.Text = address;txt09.Text = birthday.ToString();txt07.Text = email;cbo01.Text = gradename;txt08.Text = identitycard;}}}

树状显示学生信息：

 public partial class FrmInfo : Form{public FrmInfo(){InitializeComponent();}StudentBLL sbl = new StudentBLL();GradeBLL bll = new GradeBLL();private void FrmInfo_Load(object sender, EventArgs e){TreeNode tn= new TreeNode("全部");DataTable table=bll.GradeInfo();foreach (DataRow item in table.Rows){TreeNode node = new TreeNode();node.Text = item["gradename"].ToString();TreeNode child = new TreeNode();child.Text = "男";child.Tag = "1";TreeNode childs = new TreeNode();childs.Text = "女";childs.Tag = "0";node.Nodes.Add(child);node.Nodes.Add(childs);//node.Nodes.Add("男");//node.Nodes.Add("女");tn.Nodes.Add(node);  }tvList.Nodes.Add(tn);}private void tvList_AfterSelect(object sender, TreeViewEventArgs e){if(tvList.SelectedNode.Level==0){dgvList.DataSource = sbl.Student();}else if(tvList.SelectedNode.Level==1){dgvList.DataSource=sbl.SelectStudent(tvList.SelectedNode.Text);}else if(tvList.SelectedNode.Level == 2){if(tvList.SelectedNode.Text=="男"){dgvList.DataSource = sbl.SelectStudent(tvList.SelectedNode.Parent.Text, Convert.ToString(tvList.SelectedNode.Tag));}else{dgvList.DataSource = sbl.SelectStudent(tvList.SelectedNode.Parent.Text, Convert.ToString(tvList.SelectedNode.Tag));}}}private void 修改ToolStripMenuItem_Click(object sender, EventArgs e){FrmAdd add = new FrmAdd();add.Text = "修改学生成绩";add.no = Convert.ToInt32(dgvList.SelectedRows[0].Cells[0].Value);add.pwd = dgvList.SelectedRows[0].Cells[1].Value.ToString();add.name = dgvList.SelectedRows[0].Cells[2].Value.ToString();add.gender = dgvList.SelectedRows[0].Cells[3].Value.ToString();add.gradename = dgvList.SelectedRows[0].Cells[4].Value.ToString();add.phone = dgvList.SelectedRows[0].Cells[6].Value.ToString();add.address = dgvList.SelectedRows[0].Cells[5].Value.ToString();add.birthday= (dgvList.SelectedRows[0].Cells[7].Value.ToString());add.email = dgvList.SelectedRows[0].Cells[8].Value.ToString();add.identitycard = dgvList.SelectedRows[0].Cells[9].Value.ToString();add.Show();}private void 取消ToolStripMenuItem_Click(object sender, EventArgs e){FrmResult fr = new FrmResult();fr.no = Convert.ToInt32(dgvList.SelectedRows[0].Cells[0].Value);fr.name = dgvList.SelectedRows[0].Cells[2].Value.ToString();fr.Show();}}

添加学生成绩窗体：

  public partial class FrmResult : Form{public FrmResult(){InitializeComponent();}GradeBLL bll = new GradeBLL();SubjectBLL sbl = new SubjectBLL();ResultBLL rbl = new ResultBLL();private void FrmResult_Load(object sender, EventArgs e){cbosubject.ValueMember = "subjectid";cbosubject.DisplayMember = "subjectname";cbosubject.DataSource = sbl.SubjectInfo();txtname.Text = name;}public int no;public string name;private void btnAdd_Click(object sender, EventArgs e){Result rt = new Result();rt.StudentNo = no;rt.SubjectId=Convert.ToInt32(cbosubject.SelectedValue);rt.StudentResult = Convert.ToInt32(txtresult.Text);rt.ExamDate = txttime.Text;bool flag=rbl.AddResult(rt);if(flag){MessageBox.Show("添加成功！");}}}

ComboBox联动:

 public partial class FrmScore : Form{public FrmScore(){InitializeComponent();}SubjectBLL bll = new SubjectBLL();GradeBLL gbl = new GradeBLL();private void cbograde_SelectedIndexChanged(object sender, EventArgs e){int gradeid = Convert.ToInt32(cbograde.SelectedValue);cbosubject.ValueMember = "subjectid";cbosubject.DisplayMember = "subjectname";cbosubject.DataSource = bll.SubjectALL(gradeid);}private void FrmScore_Load(object sender, EventArgs e){cbograde.ValueMember = "gradeid";cbograde.DisplayMember = "gradename";cbograde.DataSource= gbl.GradeInfo();}}

根据科目和年级查询和修改学生成绩窗体：

 public partial class FrmSelectResult : Form{public FrmSelectResult(){InitializeComponent();}GradeBLL bll = new GradeBLL();SubjectBLL sbl = new SubjectBLL();ResultBLL rbl = new ResultBLL();private void FrmSelectResult_Load(object sender, EventArgs e){cbo01.ValueMember = "gradeid";cbo01.DisplayMember = "gradename";cbo01.DataSource = bll.GradeInfo();cbo02.ValueMember = "subjectid";cbo02.DisplayMember = "subjectname";cbo02.DataSource = sbl.SubjectInfo();cbo03.ValueMember = "subjectid";cbo03.DisplayMember = "subjectname";cbo03.DataSource = sbl.SubjectInfo();DataTable table = rbl.SelectResult();dgvList.DataSource = table;}DataTable table;private void button1_Click(object sender, EventArgs e){if(txt01.Text==""){table = rbl.SelectResult(Convert.ToInt32(cbo02.SelectedValue));} else{table = rbl.SelectResult(txt01.Text);}dgvList.DataSource = table;}private void dgvList_DoubleClick(object sender, EventArgs e){lbl01.Text = dgvList.SelectedRows[0].Cells[0].Value.ToString();cbo03.Text = dgvList.SelectedRows[0].Cells[1].Value.ToString();txt02.Text = dgvList.SelectedRows[0].Cells[2].Value.ToString();txt03.Text = dgvList.SelectedRows[0].Cells[3].Value.ToString();}private void button2_Click(object sender, EventArgs e){Result result = new Result();result.StudentNo = Convert.ToInt32(dgvList.SelectedRows[0].Cells[4].Value);result.StudentResult = Convert.ToInt32(txt02.Text);result.SubjectId = Convert.ToInt32(cbo03.SelectedValue);result.ExamDate = txt03.Text;bool flag= rbl.UpdateResult(result);if(flag){MessageBox.Show("修改成功");DataTable table = rbl.SelectResult();dgvList.DataSource = table;}}private void cbo01_SelectedIndexChanged(object sender, EventArgs e){int gradeid = Convert.ToInt32(cbo01.SelectedValue);cbo02.ValueMember = "subjectid";cbo02.DisplayMember = "subjectname";cbo02.DataSource = sbl.SubjectALL(gradeid);}}

这个需要你自己多练习，现在学习是在学习思想，记得没事多练习.......

转载于:https://www.cnblogs.com/xieweikai/p/6826566.html