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DataReaderdr.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DataSetstring 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DataSetadapter.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DataTableadapter.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 DataSetadapter.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DataGridDataGrid1.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();