数据库编程题思路.docx

实体类/包含三层代码里需要用到的属性，传递的参数using System;using System.Data;using System.Configuration;using System.Web;using System.Web.Security;using System.Web.UI;using System.Web.UI.WebControls;using System.Web.UI.WebControls.WebParts;using System.Web.UI.HtmlControls;namespace dep.model /定义命名空间 其他的页面才能引用 才能传递参数 public class Department public Department() private int _departmentID; /字段是私有的，无法直接读取和修改 public int DepartmentID /通过封装公有的get/set方法 分别读取修改 get return _departmentID; set _departmentID = value; private string _departmentName; public string DepartmentName get return _departmentName; set _departmentName = value; private string _leaderName; public string LeaderName get return _leaderName; set _leaderName = value; private string _office; public string Office get return _office; set _office = value; 业务逻辑层的代码：using System;using System.Data;using System.Configuration;using System.Web;using System.Web.Security;using System.Web.UI;using System.Web.UI.WebControls;using System.Web.UI.WebControls.WebParts;using System.Web.UI.HtmlControls;using dep.model; /需要引用一下实体类using dep.dal; /需要引用数据访问层using System.Collections.Generic; /可以使用List泛型namespace dep.bll /声明的命名空间，也就是其他页面进行引用的类的名字 public class DepartmentBll public DepartmentBll() /这是构造方法 private readonly DepartmentDal deptDal = new DepartmentDal(); /声明一个dal的实例，只有声明了才能用，也就是说把抽象概念变成具体的对象 public bool insert(Department dept) return deptDal.Insert(dept); /调用数据访问层的Insert方法，通过实例调用，也就是deptDal这个实例，这是在上头实例化中声明的实例名（粗斜体）。 public List Display() return deptDal.DisplayAll(); /调用数据访问层的displayAll方法 数据访问层using System;using System.Data;using System.Configuration;using System.Web;using System.Web.Security;using System.Web.UI;using System.Web.UI.WebControls;using System.Web.UI.WebControls.WebParts;using System.Web.UI.HtmlControls;using System.Data.SqlClient; /用到Sqlconnection对象的时候需要引用这个！using dep.model; /引用实体类using System.Collections.Generic; /结果集 需要引用 才能用List泛型namespace dep.dal /这是这个页面定义的命名空间 public class DepartmentDal string con; SqlConnection cn; public DepartmentDal() /这是在这个类的默认构造方法里，也就是说声明类对象的时候就会自动执行 con = ConfigurationManager.ConnectionStringsConString.ConnectionString; /从web.config配置文件读入数据库连接配置 cn = new SqlConnection(con); /实例化连接对象 public bool Insert(Department dept) /增加操作,成功返回true到业务逻辑层bal try cn.Open(); /sql语句根据自己的需要进行修改 string sql = insert into Department values( + dept.DepartmentID.ToString() + , + dept.DepartmentName + , + dept.LeaderName + , + dept.Office + ); SqlCommand cmd = new SqlCommand(sql, cn);/实例化查询对象，sql是各种查询语句，cn是连接的名字 cmd.ExecuteNonQuery(); /执行查询 cn.Close(); return true; catch return false; public bool Delete(Department dept) /删除 try cn.Open(); string sql=delete from Department where DepartmentID=+dept.DepartmentID.ToString()+); SqlCommand cmd = new SqlCommand(sql, cn); cmd.ExecuteNonQuery(); cn.Close(); return true; catch return false; public List DisplayAll() /查询 查询的结果是个结果集 List depts = new List(); /需要有引用才能用！ string sql = select * from department; SqlDataAdapter da = new SqlDataAdapter(sql, cn);/dataset的固定模式记住 DataSet ds = new DataSet(); da.Fill(ds, dept);/把da填充到ds DataTable dt = ds.Tablesdept; /实例一个表对象 for (int i = 0; i dt.Rows.Count; i+) DataRow row = dt.Rowsi; /实例化行对象 Department dept = GetDeptFromDataRow(row); /把数据一行一行的读入进表对象（调用的方法写在下面） depts.Add(dept); return depts; private Department GetDeptFromDataRow(DataRow row) /一个集合形式 Department dept = new Department(); dept.D