Ado.net 2.0学习

Ado.net 2.0学习

所谓ADO.NET是一组用于和数据源进行交互的面向对象类库,就是访问数据库SQL Access XML Excel等数据源而已。

访问数据首先就要建立到操作对象的连接,这就是connection对象,通常用的访问SQL Server的叫SqlConnection,访问Access的叫OleDbConnection.

连接上了,自然就要执行Sql语句来操作表,这时就需要Command对象了,同样的也分SqlCommand(访问SQLServer),OleDbCommand(访问Access或其它).

执行Sql Command的成功后有结果返回,此时需要装结果的容器了,如果是数据表则需要,一是DataReader另一个是DataSet.

DataReader来自于Command.ExecuteReader()返回,DataSet来自于DataAdapter.Fill(ds, "dstablename")Fill.同是存放表的.

为何要分两种,因为DataSet经过Fill操作后是将表拷贝至内存了,关闭了连接,DataReader只是打开联接,数据需要由前至后的一条条读出.在不同的应用环境需要时各有所长,特别是dataset在大量请求负载处理时将会显现出超强的性能优势,采用SqlDataAdapter.Update操作的SqlCommandBuilder来更新删除,修改一些大批量数据,或用SQL语句实现修改多列多项有困难的需求时.

 

使用Sql server数据库时常会用到的在webconfig中定义connectionStrings 如下

 

"Northwind" connectionString="Server=localhost;Integrated Security=True;Database=Northwind;Persist Security Info=True" providerName="System.Data.SqlClient" />

引用这个定义则用如下语句

string connectionString =ConfigurationManager.ConnectionStrings["Northwind"].ConnectionString;

 

通常使用SqlDataAdapter(),读取数据用GridView显示如下:

string connStr = ConfigurationManager.ConnectionStrings["Northwind"].ConnectionString;

SqlConnection myConnection = new SqlConnection(connStr);

myConnection.Open();

SqlDataAdapter da = new SqlDataAdapter("SELECT * FROM Customers; SELECT * FROM Orders;", myConnection); //注意两个表读

DataSet ds = new DataSet();

da.Fill(ds, "Customers");

CustomersGridView.DataSource = ds.Tables[0];//ds.Tables["Customers"]

CustomersGridView.DataBind();

OrdersGridView.DataSource = ds.Tables[0];//ds.Tables["Customers"]

OrdersGridView.DataBind();

myConnection.Close();

 

通常使用SqlDataReader(),读取数据用GridView显示时如下:

string connStr = ConfigurationManager.ConnectionStrings["Northwind"].ConnectionString;

SqlConnection myConnection = new SqlConnection(connStr);

myConnection.Open();

SqlCommand command = new SqlCommand("Select * FROM Customers", myConnection);

SqlDataReader dr=command.ExecuteReader();

GridView1.DataSource = dr;

GridView1.DataBind();

myConnection.Close();

 

一个基本的Sql server 采用DataReader()操作增,,,读的类,C#代码如下

using System;

 using System.Data;

 using System.Data.SqlClient;

 class SqlCommandDemo

 {

     SqlConnection conn;

 

     public SqlCommandDemo()  //构造

     {

         // 建立联接方法

         conn = new SqlConnection("Data Source=(local);Initial Catalog=Northwind;Integrated Security=SSPI");

     }

 

     // 主程序

     static void Main()

     {

         SqlCommandDemo scd = new SqlCommandDemo();

         Console.WriteLine();

         Console.WriteLine("Categories Before Insert");

         Console.WriteLine("------------------------");

         //ExecuteReader 读出显示

         scd.ReadData();

         // ExecuteNonQuery 方法新建插入一条数据

         scd.InsertData();

         Console.WriteLine();

         Console.WriteLine("Categories After Insert");

         Console.WriteLine("------------------------------");

        scd.ReadData(); 

         // use ExecuteNonQuery 更新

         scd.UpdateData();

         Console.WriteLine();

         Console.WriteLine("Categories After Update");

         Console.WriteLine("------------------------------");

         scd.ReadData();

         // use ExecuteNonQuery 删除方法

         scd.DeleteData();

 

         Console.WriteLine();

         Console.WriteLine("Categories After Delete");

         Console.WriteLine("------------------------------");

 

         scd.ReadData();

 

         // use ExecuteScalar 统计方法

         int numberOfRecords = scd.GetNumberOfRecords();

 

         Console.WriteLine();

         Console.WriteLine("Number of Records: {0}", numberOfRecords);

     }

//以下各子方法

     public void ReadData()   //读出

     {

        SqlDataReader rdr = null;

 

         try

         {

             conn.Open();

 

             // 1. 初始化一个SqlCommand对象

             SqlCommand cmd = new SqlCommand("select CategoryName from Categories", conn);

 

             // 2. 读出

             rdr = cmd.ExecuteReader();

 

             // 遍历所有数据输出

             while (rdr.Read())

             {

                 Console.WriteLine(rdr[0]);

             }

         }

         finally

         {

             // 关闭

             if (rdr != null)

             {

                 rdr.Close();

             }

 

             // 且关闭联接

             if (conn != null)

             {

                 conn.Close();

             }

         }

     }

 

     public void InsertData()     //插入

     {

         try

         {

             conn.Open();

 

             // 准备参数

             string insertString = @"insert into Categories (CategoryName, Description)values ('Miscellaneous', 'Whatever doesn''t fit elsewhere')";

 

             // 1. 初始化SqlCommand,并连接conn

             SqlCommand cmd = new SqlCommand(insertString, conn);

             // 2. 执行

             cmd.ExecuteNonQuery();

         }

         finally

         {

             // 关闭

             if (conn != null)

             {

                 conn.Close();

             }

         }

     }

 

     public void UpdateData()  //更新

     {

         try

         {

             conn.Open();

             // 参数

             string updateString = @"update Categories set CategoryName = 'Other' where CategoryName = 'Miscellaneous'";

             // 1.初始化

             SqlCommand cmd = new SqlCommand(updateString);

             // 2. 连接conn

             cmd.Connection = conn;

             // 3.执行

             cmd.ExecuteNonQuery();

        }

         finally

         {

             // 关闭

             if (conn != null)

             {

                 conn.Close();

             }

         }

     }

 

     public void DeleteData()   //删除

     {

         try

         {

             conn.Open();

             //准备参数

             string deleteString = @"delete from Categories where CategoryName = 'Other'";

             // 1. command

             SqlCommand cmd = new SqlCommand();

             // 2. 绑定

             cmd.CommandText = deleteString;

             // 3. 连接

             cmd.Connection = conn;

             // 4. 执行

             cmd.ExecuteNonQuery();

         }

         finally

         {

             // 关闭

             if (conn != null)

             {

                 conn.Close();

             }

         }

     }

 

     public int GetNumberOfRecords()  //统计

     {

         int count = -1;

         try

         {

             conn.Open();

             // 1. 初始化一个command

             SqlCommand cmd = new SqlCommand("select count(*) from Categories", conn);

             // 2. 执行

             count = (int)cmd.ExecuteScalar();

         }

         finally

         {

            // 关闭

             if (conn != null)

             {

                 conn.Close();

             }

         }

         return count;

     }

 }

 

采用SqlDataAdapter()SqlCommandBuilder操作增,,,,C#代码如下

private void UseCommandBuilder()

{

 string connectionString = "Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=Northwind;Data Source=LAP800";

 SqlConnection connection = new SqlConnection(connectionString);

 connection.Open();

 try {

   SqlCommand command = new SqlCommand("SELECT * FROM Customers", connection);

   SqlDataAdapter adapter = new SqlDataAdapter(command);

   SqlCommandBuilder builder = new SqlCommandBuilder(adapter);

   Console.WriteLine(builder.GetInsertCommand().CommandText);

   Console.WriteLine(builder.GetUpdateCommand().CommandText);

   Console.WriteLine(builder.GetDeleteCommand().CommandText);

   DataTable table = new DataTable();

   adapter.Fill(table); //读出数据,平常用时会Fill给一个dataset,

   DataRow row = table.NewRow;

   row("CustomerID") = "PAULK";

   row("CompanyName") = "Pauly's Edibles";

   row("ContactName") = "Paul Kimmel";

   row("ContactTitle") = "The Fat Man";

   table.Rows.Add(row);   //插入上面生成的一条数据

   DataRow[] results = table.Select("CustomerID = 'ALFKI'");

   results(0)("Region") = "DE";   //修改数据

   DataRow[] deleteThese = table.Select("CustomerID = 'FARLA'");

   foreach (int row in deleteThese) {

     row.Delete();   //删除数据

   }

   adapter.Update(table);

   table.AcceptChanges();

 

 } catch (Exception ex) {

   Debug.WriteLine(ex.Message);

   throw;

 } finally {

   connection.Close();

 }

 

收集

System.Data.SqlClient.SqlConnection 常用的一些连接字符串(C#代码)

SqlConnection conn = new SqlConnection("Server=(local);Integrated Security=SSPI;database=Pubs");

SqlConnection conn = new SqlConnection("server=(local)\\NetSDK;database=pubs;Integrated Security=SSPI");

SqlConnection conn = new SqlConnection("Data Source=localhost;Integrated Security=SSPI;Initial Catalog=Northwind;");

SqlConnection conn = new SqlConnection(" data source=(local);initial catalog=xr;integrated security=SSPI;persist security info=False;workstation id=XURUI;packet size=4096; ");

SqlConnection conn  = new System.Data.SqlClient.SqlConnection("Persist Security Info=False;Integrated Security=SSPI;database=northwind;server=mySQLServer");

SqlConnection conn = new SqlConnection( " uid=sa;pwd=passwords;initial catalog=pubs;data source=127.0.0.1;Connect Timeout=900");

 

System.Data.OleDb.OleDbConnection常用的一些连接字符串(C#代码)

OleDbConnection conn = new OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\MyWeb\81\05\GrocerToGo.mdb");

OleDbConnection conn = new OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Password=;User ID=Admin;Data Source=grocertogo.mdb;");

OleDbConnection conn = new OleDbConnection("Provider=MSDAORA; Data Source=ORACLE8i7;Persist Security Info=False;Integrated Security=yes");

OleDbConnection conn = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0; Data Source=c:\bin\LocalAccess40.mdb");

OleDbConnection conn = new OleDbConnection("Provider=SQLOLEDB;Data Source=MySQLServer;Integrated Security=SSPI");

posted on 2007-01-30 15:21 无极.net 阅读( ...) 评论( ...) 编辑 收藏

转载于:https://www.cnblogs.com/circlesport/archive/2007/01/30/634714.html

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