?今天我們來講講分層開發，你從標題能不能簡單的認識一下什么是分層呢？

不懂也沒關系，接下來我來給你講講。

第一章 軟件系統的分層開發

（1）其實分層模式可以這樣定義：將解決方案中功能不同的模塊分到不同的項目中實現，每一層中的組件應保持內聚性，每一層都應該與它下面的各層保持松耦合。

?????? 分層模式是最常見的一種架構模式，甚至可以說分層模式是很多架構模式的基礎。

?????? 數據訪問層：

???????? ?這一層處于最底層，負責與數據庫的交互，也成為DAL（Data Access Layer）

?????? 表示層：

???????? 這一層直接與用戶打交道，負責顯示或者獲取數據，也稱為UI（User Interface Layer）

（2）.NET程序集是任何.NET Framework應用程序的基本構造塊。程序集由描述它的程序集清單（包含版本號，程序集名稱等），類型元數據，MSIL代碼和資源組成，

??????? 這些部分都分布在一個文件中。

??????? 程序集主要包括以下兩類：

????????（1）可執行文件，即.exe文件?? （2）類庫文件，即.dll文件

（3）程序集，解決方案，項目和命名空間的關系如下：

??????? （1）一個解決方案可以由一個或者多個項目組成，這些項目可以是Windows應用程序，類庫等。

??????? （2）一個程序集可以包含多個命名空間，程序集默認的命名空間名稱就是程序集的名稱。

????????（3）命名空間是組織C#程序的一種邏輯架構，一個命名空間可以有多個類。

（4）分層開發的優點：

?????? （1）代碼的復用（2）分離開發人員的關注（3）無損提換（4）降低了系統間的依賴

（5）異常處理

?? 常見的異常類型:

????? System.Exception :這個類提供系統異常和應用程序異常之間的區別

??????System.SQLException :當SQL Server返回警告或者錯誤時引發的異常

????? ArgumentNullException :當將空引用傳遞給不接受它作為有效參數的方法時引發的異常

????? FileNotFoundException :試圖訪問磁盤上不存在的文件失敗時引發的異常

????? IOException :當出現I/O錯誤時，引發此異常

????? ApplicationException :在應用程序執行過程中檢測到由應用程序定義的異常

? 異常類的常用屬性：

???? Message :提供引起異常的詳細信息

???? Source :表示導致異常發生的應用程序或者對象的名稱

???? StackTrace :提供在棧堆上所調用方法的詳細信息，并首先顯示最近調用的方法

???? InnerException :對內部異常的引用，如果此異常基于前一個異常，則內部異常指最初發生的異常

（6）異常處理回顧

??? 語法：

???

try-catchtry {//可能引發異常的工作代碼 } catch(異常對象) {//異常處理 }try-finallytry {//可能引發異常的工作代碼 } finally {//清理相關對象的代碼 }try-catch-finallytry { //可能引發異常的工作代碼 } catch(異常對象) {//異常處理 } finally {//清理相關對象的代碼 }

?

上面的文字都是枯燥的，接下來用代碼來演示一下：

/// <summary>/// 數據訪問層/// </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("訪問數據庫失敗" + ex.Message);}catch (DivideByZeroException ex){throw new Exception("除數不能為0" + ex.Message);}catch (Exception ex){throw new Exception("失敗" + ex.Message);}} /// <summary>/// 數據訪問層/// </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典型應用：實體類

（1）實體類是業務對象的基礎，它用面向對象的思想消除了關系數據與對象之間的差異

???實體類:

/// <summary>/// 部門表/// </summary>public class Department{public int BId { get; set; }public int BName{ get; set; }} /// <summary>/// 員工表/// </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>/// 任務內容表/// </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; }} 數據訪問層： 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;}}

?

接下來是一個輔助類，因為以后要經常用，有能力的自己寫一個工具吧！

public static class SQLHelper{//用靜態的方法調用的時候不用創建SQLHelper的實例//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>/// 執行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);}//可以使用存儲過程的ExecuteNonquerypublic static int ExecuteNonQuery(string cmdTxt, CommandType cmdtype, params SqlParameter[] parames){//判斷腳本是否為空 ，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存儲過程方法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的行為加進來。當reader釋放資源的時候，con也被一塊關閉return cmd.ExecuteReader(System.Data.CommandBehavior.CloseConnection);}}public static DataTable ExecuteDataTable(string sql, params SqlParameter[] parames){return ExecuteDataTable(sql, CommandType.Text, parames);}//調用存儲過程的類，關于(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">第一個參數，SQLServer語句</param>/// <param name="parames">第二個參數，傳遞0個或者多個參數</param>/// <returns></returns>public static object ExecuteScalar(string cmdTxt, params SqlParameter[] parames){return ExecuteScalar(cmdTxt, CommandType.Text, parames);}//可使用存儲過程的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();}}}//調用存儲過程的DBHelper類（關于ExeceutScalar,包含事務,只能處理Int類型，返回錯誤號）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;}}}}
數據訪問層： public class TaskDAL{//查詢信息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;}//根據條件查詢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;}//加載任務名稱public DataTable RInfo(){string sql = "select Contents from Task ";DataTable table = SQLHelper.ExecuteDataTable(sql);return table;}}

在這里再引用一個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>

窗體加載：

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("請輸入你要添加的文本");}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語句錯誤");}catch (Exception){MessageBox.Show("程序出錯");}}}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("請選擇要修改的文本");}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語句錯誤");}catch (Exception){MessageBox.Show("程序出錯");}}} 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應用程序運行所依賴的常量，這些常量可能會隨著多種因素的變化而變化，所以將這些信息寫在配置文件中，由程序來動態讀取。
讀取連接字符串的語法如下：

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

（2）const和readonly的區別

?? （1）readonly只能修飾類變量?? const修飾成員變量和局部變量

???（2）readonly在運行時賦值，const在編譯時賦值

?? （3）const只能修飾值類型和特殊的引用類型? readonly可以修飾任何類型

第三章 提高系統性能：從數據訪問開始

（1）using語句

????? ?using的作用：（1）導入命名空間（2）釋放實現了disposable接口的對象非托管資源

?????? 語法：

?????? using(SqlConnection con=new SqlConnection(constr))

??????? {

?????????? //數據庫操作代碼.......

?????????}

（2）參數化命令（防止SQL注入攻擊）

???語法：

（1）使用參數名和參數類型進行設置public SqlParameter Add(string parameterName,SqlDbType slDbType);public SqlParameter Add(string parameterName,SqlDbType paraValue,int size);（2）使用SqlParameter對象進行填充public SqlParameter Add(SqlParameter value); //添加單個參數public void AddRange(SqlParameter[] values); //添加多個參數

?

??? （3）SqlParameter類的常用屬性

???????

DbType :獲取或設置參數的DbTypeDirection :獲取或設置一個值，該值表示參數是只可輸入，是可輸出，還是雙向存儲過程返回值參數IsNullable :獲取或設置一個值，該值指示參數是否接受空值ParameterName :獲取或設置SqlParameter的名稱Size :獲取或設置列中數據的最大值（以字節為單位）SqlDbType :獲取或設置參數的SqlDbTypeValue ：獲取或設置該參數的值

第四章 業務的擴展：三層架構

（1）業務邏輯層BLL（Business Logic Layer）

實體類：

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; }}

數據訪問層DAL：

?

/// <summary>/// 班級表/// </summary>public class GradeDAL{//加載班級信息public DataTable GradeInfo(){ string sql = "select * from Grade";DataTable table=SQLHelper.ExecuteDataTable(sql);return table;}} public class MyTool{/// <summary>/// DataSetToList/// </summary>/// <typeparam name="T">轉換類型</typeparam>/// <param name="dataSet">數據源</param>/// <param name="tableIndex">需要轉換表的索引</param>/// <returns></returns>public List<T> DataTableToList<T>(DataTable dt){//確認參數有效if (dt == null )return null;List<T> list = new List<T>();for (int i = 0; i < dt.Rows.Count; i++){//創建泛型對象T _t = Activator.CreateInstance<T>();//獲取對象所有屬性PropertyInfo[] propertyInfo = _t.GetType().GetProperties();for (int j = 0; j < dt.Columns.Count; j++){foreach (PropertyInfo info in propertyInfo){//屬性名稱和列名相同時賦值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>/// 成績表/// </summary>public class ResultDAL{//根據科目條件查詢成績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;}//根據姓名查詢成績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;}//查詢全部成績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;}// 修改學生成績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;}//添加學生成績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>/// 學生表/// </summary>public class StudentDAL{//Login登錄 public bool IsLogin(Student stu){#region 方式一：登錄//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：登錄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}//根據條件學生信息// StudentNo, LoginPwd, StudentName, Gender, GradeId, Phone, Address, Birthday, Email,public List<Student> StudentInfo(int gradeid){#region 查詢一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 查詢一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}// 添加學生信息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;}//修改學生信息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;}}//查詢全部學生信息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;}//條件查詢學生信息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;}}

業務邏輯層BLL：

public class GradeBLL{GradeDAL dal = new GradeDAL();//加載年級信息public DataTable GradeInfo(){return dal.GradeInfo();} } public class ResultBLL{ResultDAL dal = new ResultDAL();public DataTable SelectResult(int subjectid){return dal.SelectResult(subjectid);}//條件查詢public DataTable SelectResult(string studentname){return dal.SelectResult(studentname);}//查詢全部public DataTable SelectResult(){return dal.SelectResult();}//修改成績public bool UpdateResult(Result result){return dal.UpdateResult(result);}//添加學生成績public bool AddResult(Result result){return dal.AddResult(result);}} /// <summary>/// 邏輯層/// </summary>/// public class StudentBLL{StudentDAL dal = new StudentDAL();//登錄public bool IsLogin(Student stu){//Common com = new Common();//string temp = com.GetMD5String(stu.LoginPwd);//stu.LoginPwd = temp;return dal.IsLogin(stu);}顯示學生信息public List<Student> StudentInfo(int gradeid){return dal.StudentInfo(gradeid);}public List<Student> StudentInfo(string name){return dal.StudentInfo(name);}//增加學生信息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{//加載科目信息SubjectDAL sdl = new SubjectDAL();public DataTable SubjectInfo(){return sdl.SubjectInfo();}public List<Subject> SubjectALL(int gradeid){return sdl.SubjectALL(gradeid);}}

表示層DAL：

登錄窗體：

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");}}}

主窗體：

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 添加學生成績ToolStripMenuItem_Click(object sender, EventArgs e){FrmResult result = new FrmResult();result.MdiParent = this;result.Show();}private void 查詢學生成績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();}}

添加和修改學生信息窗體：

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();//添加學生private void btn01_Click(object sender, EventArgs e){//創建一個學生對象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;//把對象添加到數據表中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();//加載班級信息private void FrmAdd_Load(object sender, EventArgs e){cbo01.ValueMember = "GradeId";cbo01.DisplayMember = "gradeName";cbo01.DataSource= gbl.GradeInfo();if (this.Text == "添加學生信息"){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;}}}

樹狀顯示學生信息：

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 = "修改學生成績";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();}}

添加學生成績窗體：

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聯動:

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();}}

根據科目和年級查詢和修改學生成績窗體：

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);}}

這個需要你自己多練習，現在學習是在學習思想，記得沒事多練習.......

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轉載于:https://www.cnblogs.com/xieweikai/p/6826566.html

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