数据库方面的操作示例

1  连接SQL Server数据库示例

// 连接字符串

 string ConnectionString = System.Configuration.ConfigurationSettings.AppSettings["ConnectionSqlServer"];

// 创建SqlConnection对象

 SqlConnection connection = new SqlConnection(ConnectionString); 

  

 try

 {

  // 打开数据库连接

  connection.Open();         

  myLabel.Text = "连接数据库成功";

 }

 catch

 {

  myLabel.Text = "连接数据库失败";

 }

 finally

 {

         // 关闭数据库连接

        connection.Close();         

 }

 <appSettings>

    <add key="ConnectionSqlServer" value="Server=(local);User id=sa;Pwd=sa;Database=Northwind"></add>

 <add key="ConnectionSqlServer1" value="Server=(local);User id=sa;Pwd=sa;"></add>

 <add key="ConnectionSqlServer_tempdb" value="Server=(local);User id=sa;Pwd=sa;Database=tempdb"></add>

 <add key="ConnectionDB2" value="DATABASE=SAMPLE;UID=username;PWD=password"></add>

 <add key="ConnectionOracle" value="Data Source=Oracle8i;Integrated Security=yes"></add>

  </appSettings> 

  <system.web>



 2  // 连接到 ACCESS 的连接字符串

    string ConnStr = "Provider=Microsoft.Jet.OLEDB.4.0; Data source=" + Server.MapPath("grocertogo.mdb");

    // 使用OleDb .NET数据提供程序创建连接

    OleDbConnection oleConnection = new OleDbConnection(ConnStr);

    try

    {

     // 打开数据库连接

     oleConnection.Open();

     // 显示连接成功信息

     myLabel.Text = "Access数据库连接状态：" + oleConnection.State;

    }

    catch(Exception ex)

    {

     // 如果出现异常，显示异常信息

     myLabel.Text = "Access数据库连接状态：" + ex.ToString();

    }

    finally

    {

     // 关闭数据库连接

     oleConnection.Close(); 

    }



3 // 连接到 Oracle 数据库示例



    string ORACLE_ConnStr = "Data Source=Oracle8i;Integrated Security=yes";

    // 创建 OracleConnection 对象

    OracleConnection oConnection = new OracleConnection(ORACLE_ConnStr);

    try

    {

     oConnection.Open();

     myLabel.Text = "连接到 Oracle 数据库";

    }

    catch(Exception ex)

    {

     myLabel.Text = ex.ToString();

    }

    finally

    {

     oConnection.Close();

    }  



4 SqlCommand 执行SQL命令示例

    string ConnStr = System.Configuration.ConfigurationSettings.AppSettings["ConnectionSqlServer"];

    // 创建SqlConnection对象

    // 创建Command对象

    SqlConnection thisConnection = new SqlConnection(ConnStr);

    SqlCommand thisCommand = new SqlCommand();

    // 关联Connection对象

    // 赋值SQL语句到CommandText属性

    // 指定命令类型是Sql语句

    thisCommand.Connection = thisConnection;

    thisCommand.CommandText = "SELECT COUNT(*) FROM Employees";

    thisCommand.CommandType = CommandType.Text;

    try

    {

     // 打开数据库连接

     thisCommand.Connection.Open();

     // 获取查询结果

     myLabel.Text = thisCommand.ExecuteScalar().ToString();

    }

    catch(SqlException ex)

    {

     // 如果出现异常，在Label标签中显示异常信息

     myLabel.Text = ex.ToString();

    }

    finally

    {

     // 关闭数据库连接

     thisCommand.Connection.Close();

    }



5  SqlDataReader 读取数据示例

   string ConnectionString = System.Configuration.ConfigurationSettings.AppSettings["ConnectionSqlServer"];

    string Sql = "SELECT LastName, FirstName FROM Employees";

    SqlConnection thisConnection = new SqlConnection(ConnectionString);

    SqlCommand thisCommand = new SqlCommand(Sql, thisConnection);

    thisCommand.CommandType = CommandType.Text;

    try

    {

     // 打开数据库连接

     thisCommand.Connection.Open();

     // 执行SQL语句，并返回DataReader对象

     SqlDataReader dr = thisCommand.ExecuteReader();

     // 以粗体显示标题

     myLabel.Text = "<b>LastName FirstName</b><br>";

     // 循环读取结果集

     while(dr.Read())

     {

      // 读取两个列值并输出到Label中

      myLabel.Text += dr["LastName"] + " " + dr["FirstName"] + "<br>";

     }

     // 关闭DataReader

     dr.Close();

    }

    catch(SqlException ex)

    {

     // 异常处理

     Response.Write(ex.ToString());

    }

    finally

    {

     // 关闭数据库连接

     thisCommand.Connection.Close();

    }



6  使用DataAdapter填充数据到DataSet

        string ConnectionString = System.Configuration.ConfigurationSettings.AppSettings["ConnectionSqlServer"];

    string Sql = "SELECT EmployeeID, LastName, FirstName,Title, TitleOfCourtesy, BirthDate FROM Employees";

    // 创建SqlConnection对象

    // 创建DataAdapter对象并初始化

    SqlConnection thisConnection = new SqlConnection(ConnectionString);

    SqlDataAdapter adapter = new SqlDataAdapter(Sql, thisConnection);

    // 创建DataSet对象

    DataSet data = new DataSet();

    // 填充数据到DataSet

    adapter.Fill(data);

    // 数据绑定

    myDataGrid.DataSource = data;

    myDataGrid.DataBind();



7 使用DataTable存储数据库表内容

    string ConnectionString = System.Configuration.ConfigurationSettings.AppSettings["ConnectionSqlServer"];

    string Sql = "SELECT EmployeeID, LastName, FirstName, BirthDate FROM Employees";

 // 创建SqlConnection、SqlDataAdapter对象

    SqlConnection thisConnection = new SqlConnection(ConnectionString);

    SqlDataAdapter adapter = new SqlDataAdapter(Sql, thisConnection);

// 创建DataTable对象

    DataTable table = new DataTable();

 // 填充数据到DataTable

    adapter.Fill(table);

    // 将DataTable绑定到DataGrid控件

    myDataGrid.DataSource = table;

    myDataGrid.DataBind();



8 将数据库数据填充到 XML 文件

// 连接字符串及 SQL 语句

    string ConnString = System.Configuration.ConfigurationSettings.AppSettings["ConnectionSqlServer"];

    string Sql = "SELECT CustomerID,CompanyName,Country FROM Customers";

    // 连接 SqlConnection 及 SqlDataAdapter 对象

    SqlConnection thisConnection = new SqlConnection(ConnString);

    SqlDataAdapter adapter = new SqlDataAdapter(Sql, thisConnection);

    // 创建 DataSet 对象

    DataSet data = new DataSet();

    // 填充 DataSet

    adapter.Fill(data, "Customers");

    // 将 DataSet 数据其及架构填充到 Xml 文件

    data.WriteXml(Server.MapPath(".") + "\\myXml.xml", XmlWriteMode.WriteSchema);

    

    // 提示填充是否成功

    Label1.Text = "填充到XML文件成功";



9 ASP.NET 使用存储过程

   // 连接字符串

   string ConnStr = System.Configuration.ConfigurationSettings.AppSettings["ConnectionSqlServer"];

   // 创建Connection对象

   SqlConnection myConn = new SqlConnection(ConnStr);

   // 创建Command对象并和Connection对象关联

   SqlCommand myCommand = new SqlCommand();

   myCommand.Connection = myConn;

   

   // 指定要执行的存储过程名称

   myCommand.CommandText = "CustomersProc";

   // 使用要执行的是存储过程

   myCommand.CommandType = CommandType.StoredProcedure;

   // 创建DataAdapter对象填充数据

   DataSet myDS = new DataSet();

   SqlDataAdapter adapter = new SqlDataAdapter(myCommand);

   adapter.Fill(myDS, "Customers");

   // 将返回的数据和DataGrid绑定显示

   myDataGrid.DataSource = myDS.Tables["Customers"];

   myDataGrid.DataBind();



10 使用带输入参数的存储过程

string ConnStr = System.Configuration.ConfigurationSettings.AppSettings["ConnectionSqlServer"];

    // 创建数据库操作对象

    SqlDataAdapter myAdapter = new SqlDataAdapter();

    SqlCommand myCommand = new SqlCommand();

    myCommand.Connection = new SqlConnection(ConnStr);

    DataTable dt = new DataTable();

    // 指定要调用的存储过程名称 "Customer_Select"

    // 指定SqlCommand对象的命令类型为 "StoredProcedure"枚举值

    myCommand.CommandText = "Customer_Select";

    myCommand.CommandType = CommandType.StoredProcedure;

    // 创建SqlParameter对象，指定参数名称、数据类型、长度及参数值

    SqlParameter para = new SqlParameter("@country", SqlDbType.NVarChar, 15);

    para.Value = DropDownList1.SelectedValue;

    

    myCommand.Parameters.Add(para);

    // 关联SqlDataAdapter与SqlCommand对象

    myAdapter.SelectCommand = myCommand;

    myAdapter.Fill(dt);

    // 绑定DataGrid

    DataGrid1.DataSource = dt;

    DataGrid1.DataBind();



11 使用带输入、输出参数的存储过程示

string ConnStr = System.Configuration.ConfigurationSettings.AppSettings["ConnectionSqlServer"];

    // 创建 Connection 和 Command 对象

    SqlConnection myConn = new SqlConnection(ConnStr);

    SqlCommand myCommand = new SqlCommand("EmployeesProc", myConn);

    // 指定要执行的命令为存储过程

    myCommand.CommandType = CommandType.StoredProcedure;

    // 增加输入参数并赋值

    myCommand.Parameters.Add("@TitleOfCourtesy", SqlDbType.NVarChar, 20);

    myCommand.Parameters["@TitleOfCourtesy"].Value = myDropDownList.SelectedItem.Text;

    myCommand.Parameters["@TitleOfCourtesy"].Direction = ParameterDirection.Input;

    // 增加输出参数

    myCommand.Parameters.Add("@empCount", SqlDbType.Int);

    myCommand.Parameters["@empCount"].Direction = ParameterDirection.Output;

    // 创建 DataAdapter 对象填充数据

    DataSet myDS = new DataSet();

    SqlDataAdapter adapter = new SqlDataAdapter(myCommand);

    adapter.Fill(myDS, "Customers");

    // 使用 Label 控件显示输出参数的输出值

    rtnLabel.Text = myCommand.Parameters["@empCount"].Value.ToString();

    // 将返回的数据和 DataGrid 绑定显示

    myDataGrid.DataSource = myDS.Tables["Customers"];

    myDataGrid.DataBind();



12 获得数据库中表的数目和名称 获取服务器端数据库列表

string listQuery = "SELECT name FROM sysobjects WHERE xtype = 'U'";

string sumQuery = "SELECT COUNT(*) FROM sysobjects WHERE xtype = 'U'



string db_query = "sp_helpdb";



13 保存图片到SQL Server数据库示例

 // HttpPostedFile对象，用于读取图象文件属性

     HttpPostedFile UpFile = UP_FILE.PostedFile;

     // FileLength 变量存储图片的字节大小

     int FileLength = UpFile.ContentLength;

     try

     {

    if (FileLength == 0)

    {

     txtMessage.Text = "<b>您未选择上传的文件</b>";

    }

    else

    {

     // 创建存储图片文件的临时 Byte 数组

     Byte[] FileByteArray = new Byte[FileLength];

     // 建立数据流对象

     Stream StreamObject = UpFile.InputStream;  

    

     // 读取图象文件数据，FileByteArray为数据储存体，0为数据指针位置、FileLnegth为数据长度

     StreamObject.Read(FileByteArray,0,FileLength);  

     // 数据库操作

     string ConnStr = System.Configuration.ConfigurationSettings.AppSettings["ConnectionSqlServer"];

     string query = "INSERT INTO ImageTable (ImageData, ImageContentType, ImageDescription, ImageSize) VALUES (@ImageData, @ImageContentType, @ImageDescription, @ImageSize)";

     SqlCommand myCommand = new SqlCommand(query, new SqlConnection(ConnStr));

     // 添加各项参数并赋值

     myCommand.Parameters.Add("@ImageData", SqlDbType.Image);

     myCommand.Parameters.Add("@ImageContentType", SqlDbType.VarChar, 50);

     myCommand.Parameters.Add("@ImageDescription", SqlDbType.VarChar, 200);

     myCommand.Parameters.Add("@ImageSize", SqlDbType.BigInt);

     myCommand.Parameters["@ImageData"].Value = FileByteArray;

     myCommand.Parameters["@ImageContentType"].Value = UpFile.ContentType;

     myCommand.Parameters["@ImageDescription"].Value = txtDescription.Text;

     myCommand.Parameters["@ImageSize"].Value = FileLength;

     

     // 执行数据库操作

     myCommand.Connection.Open();

     myCommand.ExecuteNonQuery();

     myCommand.Connection.Close();

     // 提示上传成功

     txtMessage.Text = "<b>上传文件成功</b>";

    }

   } 

   catch (Exception ex) 

   {

    // 使用 Label 标签显示异常

    txtMessage.Text = ex.Message.ToString();

   }



14 获得插入记录标识号的示例

// 数据库连接字符串

    string ConnStr = System.Configuration.ConfigurationSettings.AppSettings["ConnectionSqlServer"];

    // 创建插入SQL语句及调用@@identity函数返回标识值

    string insert_query = "insert into Categories (CategoryName,Description) values ('IT', 'Internet');"

      + "SELECT @@identity AS 'identity';";

    // 执行数据库操作

    SqlCommand myCommand = new SqlCommand(insert_query, new SqlConnection(ConnStr));

    myCommand.Connection.Open();

    myLabel.Text = myCommand.ExecuteScalar().ToString();

    myCommand.Connection.Close();

15 如何读取Excel表格中的数据

      // 获取Excep文件的完整路径

    string source = File1.Value;

    string ConnStr = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + source + ";Extended Properties=Excel 8.0";

    string query = "SELECT * FROM [Sheet1$]";

    OleDbCommand oleCommand = new OleDbCommand(query, new OleDbConnection(ConnStr));

    OleDbDataAdapter oleAdapter = new OleDbDataAdapter(oleCommand);

    DataSet myDataSet = new DataSet();

    // 将 Excel 的[Sheet1]表内容填充到 DataSet 对象

    oleAdapter.Fill(myDataSet, "[Sheet1$]");

    // 数据绑定

    DataGrid1.DataSource = myDataSet;

    DataGrid1.DataMember = "[Sheet1$]";

    DataGrid1.DataBind();