关于分层开发的数据操作层和实体层,解决即给分!

2006-04-07 01:35:11 245 阅读 AI 写同款 · GEO 优化AI 选题数据监测一键分发 ›

UML中的事物 1.事物(Things) 构成模型图的一些基本图示符号，它们表示一些面向对象的基本概念。 2.关系（Relationship）表示基本图示符号之间的关系 3.图(Diagrams) 特定的视角对系统所作的抽象描述事物是对模型中最具有代表性的成分的抽象；关系是事物结合在一起；图聚集了相关的事物 UML中的事物又有以下几类：结构事物 ... 阅读详情

请耐心看完,分不够再加!

这里有一个实体层:
using System;
using System.Data;
namespace BWebShippersDemo
{
public class DataEntity:DataSet
{
public const string ShipperTableName="Shippers";
public const string ShipperID="ShipperID";
public const string CompanyName="CompanyName";
public const string Phone="Phone";
public DataEntity()
{
this.BuildDataTable();
}
private void BuildDataTable()
{
DataTable dt=new DataTable(ShipperTableName);
dt.Columns.Add(ShipperID,typeof(int));
dt.Columns.Add(CompanyName,typeof(string));
dt.Columns.Add(Phone,typeof(string));
this.Tables.Add(dt);
}
}
}

然后有相应的数据操作层:
using System;
using System.Data;
using System.Data.SqlClient;
namespace BWebShippersDemo
{
public class DataAccess
{
private SqlCommand selectCommand;
private SqlCommand insertCommand;
private SqlCommand updateCommand;
private SqlCommand deleteCommand;
private SqlDataAdapter dsCommand;

private string connString="server=dotnet;database=northwind;integrated security=sspi";
private string selectString="select * from shippers";
private string insertString="insert into shippers (CompanyName,Phone) values (@name,@phone)";
private string updateString="update shippers set CompanyName =@name,Phone=@phone where ShipperID=@id";
private string deleteString="delete from shippers where shipperid=@id";

public DataAccess()
{
dsCommand=new SqlDataAdapter();
dsCommand.TableMappings.Add("Table",DataEntity.ShipperTableName);
}
private SqlCommand GetSelectCommand()
{
if(selectCommand==null)
{
selectCommand=new SqlCommand(selectString,new SqlConnection(connString));
}
return selectCommand;
}
private SqlCommand GetInsertCommand()
{
if(insertCommand==null)
{
insertCommand=new SqlCommand(insertString,new SqlConnection(connString));
insertCommand.Parameters.Add(new SqlParameter("@name",SqlDbType.NVarChar,40));
insertCommand.Parameters.Add(new SqlParameter("@phone",SqlDbType.NVarChar,24));
insertCommand.Parameters["@name"].SourceColumn=DataEntity.CompanyName;
insertCommand.Parameters["@phone"].SourceColumn=DataEntity.Phone;
}
return insertCommand;
}
private SqlCommand GetUpdateCommand()
{
if(updateCommand==null)
{
updateCommand=new SqlCommand(updateString,new SqlConnection(connString));
updateCommand.Parameters.Add(new SqlParameter("@id",SqlDbType.Int,4));
updateCommand.Parameters.Add(new SqlParameter("@name",SqlDbType.NVarChar,40));
updateCommand.Parameters.Add(new SqlParameter("@phone",SqlDbType.NVarChar,24));
updateCommand.Parameters["@id"].SourceColumn=DataEntity.ShipperID;
updateCommand.Parameters["@name"].SourceColumn=DataEntity.CompanyName;
updateCommand.Parameters["@phone"].SourceColumn=DataEntity.Phone;
}
return updateCommand;
}
private SqlCommand GetDeleteCommand()
{
if(deleteCommand==null)
{
deleteCommand=new SqlCommand(deleteString,new SqlConnection(connString));
deleteCommand.Parameters.Add(new SqlParameter("@id",SqlDbType.Int,4));
deleteCommand.Parameters["@id"].SourceColumn=DataEntity.ShipperID;
}
return deleteCommand;
}
public DataEntity GetShippersList()
{
DataEntity de=new DataEntity();
if(dsCommand==null)
throw new Exception("Error");
dsCommand.SelectCommand=this.GetSelectCommand();
dsCommand.Fill(de);
return de;
}
public bool InsertShippers(DataEntity de)
{
if(dsCommand==null)
throw new Exception("Error");
dsCommand.InsertCommand=this.GetInsertCommand();
dsCommand.Update(de,DataEntity.ShipperTableName);
if(de.HasErrors)
{
de.Tables[DataEntity.ShipperTableName].GetErrors()[0].ClearErrors();
return false;
}
else
{
de.AcceptChanges();
return true;
}
}
public bool UpdateShippers(DataEntity de)
{
if(dsCommand==null)
throw new Exception("Error");
dsCommand.UpdateCommand=this.GetUpdateCommand();
dsCommand.Update(de,DataEntity.ShipperTableName);
if(de.HasErrors)
{
de.Tables[DataEntity.ShipperTableName].GetErrors()[0].ClearErrors();
return false;
}
else
{
de.AcceptChanges();
return true;
}
}
public bool DeleteShippers(DataEntity de)
{
if(dsCommand==null)
throw new Exception("Error");
dsCommand.DeleteCommand=this.GetDeleteCommand();
dsCommand.Update(de,DataEntity.ShipperTableName);
if(de.HasErrors)
{
de.Tables[DataEntity.ShipperTableName].GetErrors()[0].ClearErrors();
return false;
}
else
{
de.AcceptChanges();
return true;
}
}
}
}

我的问题是这是一个数据表的访问，如果表多了,是不是每个表都得写一个实体层?那么操作层又该怎样?这样写起来是不是搞麻烦了?

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