C# 程序员参考--OLE DB 教程

OLE DB 是用于访问数据的基于 COM 的应用程序编程接口 (API)。OLE DB 支持访问以 OLE DB 提供程序可以使用的任何格式（数据库、电子表格、文本文件等）存储的数据。每个 OLE DB 提供程序从某一特定类型的数据源（例如 SQL Server 数据库、Microsoft Access 数据库或 Microsoft Excel 电子表格）公开数据。

本教程说明如何从 C# 应用程序中使用 Microsoft Access 数据库。

教程

本教程说明如何从 C# 中使用 Microsoft Access 数据库。它显示如何创建数据集并从数据库向该数据集添加表。本示例程序中使用的 BugTypes.mdb 数据库是 Microsoft Access 2000 .MDB 文件。

示例

本程序访问 BugTypes.mdb 数据库，创建一个数据集并向其中添加表，然后显示表、列和行的数目。它还显示每行的标题。

// OleDbSample.csusing System;using System.Data;using System.Data.OleDb;using System.Xml.Serialization;public class MainClass {    public static void Main ()    {            // Set Access connection and select strings.            // The path to BugTypes.MDB must be changed if you build             // the sample from the command line:#if USINGPROJECTSYSTEM            string strAccessConn = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=..\\..\\BugTypes.MDB";#else            string strAccessConn = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=BugTypes.MDB";#endif            string strAccessSelect = "SELECT * FROM Categories";             // Create the dataset and add the Categories table to it:            DataSet myDataSet = new DataSet();            OleDbConnection myAccessConn = null;            try            {                  myAccessConn = new OleDbConnection(strAccessConn);            }            catch(Exception ex)            {                  Console.WriteLine("Error: Failed to create a database connection. \n{0}", ex.Message);                  return;            }             try            {                              OleDbCommand myAccessCommand = new OleDbCommand(strAccessSelect,myAccessConn);                  OleDbDataAdapter myDataAdapter = new OleDbDataAdapter(myAccessCommand);                   myAccessConn.Open();                  myDataAdapter.Fill(myDataSet,"Categories");             }            catch (Exception ex)            {                  Console.WriteLine("Error: Failed to retrieve the required data from the DataBase.\n{0}", ex.Message);                  return;            }            finally            {                  myAccessConn.Close();            }             // A dataset can contain multiple tables, so let's get them            // all into an array:            DataTableCollection dta = myDataSet.Tables;            foreach (DataTable dt in dta)            {            Console.WriteLine("Found data table {0}", dt.TableName);            }                      // The next two lines show two different ways you can get the            // count of tables in a dataset:            Console.WriteLine("{0} tables in data set", myDataSet.Tables.Count);            Console.WriteLine("{0} tables in data set", dta.Count);            // The next several lines show how to get information on            // a specific table by name from the dataset:            Console.WriteLine("{0} rows in Categories table", myDataSet.Tables["Categories"].Rows.Count);            // The column info is automatically fetched from the database,            // so we can read it here:            Console.WriteLine("{0} columns in Categories table", myDataSet.Tables["Categories"].Columns.Count);            DataColumnCollection drc = myDataSet.Tables["Categories"].Columns;            int i = 0;            foreach (DataColumn dc in drc)            {                  // Print the column subscript, then the column's name                  // and its data type:                  Console.WriteLine("Column name[{0}] is {1}, of type {2}",i++ , dc.ColumnName, dc.DataType);            }            DataRowCollection dra = myDataSet.Tables["Categories"].Rows;            foreach (DataRow dr in dra)            {                  // Print the CategoryID as a subscript, then the CategoryName:                  Console.WriteLine("CategoryName[{0}] is {1}", dr[0], dr[1]);            }         }}

输出

BugTypes.mdb 数据库的 Categories 表包含下列信息：

当运行此示例时，屏幕上将显示下列输出：

Found data table Categories1 tables in data set1 tables in data set4 rows in Categories table2 columns in Categories tableColumn name[0] is CategoryID, of type System.Int32Column name[1] is CategoryName, of type System.StringCategoryName[1] is Bugbash StuffCategoryName[2] is Appweek BugsCategoryName[3] is .NET Framework ReportsCategoryName[4] is Internal Support
             

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