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VC database with ADO access to all Raiders1, ADO OverviewADO is Microsoft for the latest and most powerful data access paradigm designed OLE DB is an easy to use application layer interfaces. ADO allows you to write applications through OLE. DB provider to access and manipulate the data in the database server. ADO The main advantage is ease of use, speed, memory and disk less expenditure remains small. ADO in critical applications using the least network traffic, and front-end and data sources used the least number of layers, all of which are to provide a lightweight, high-performance interface. Is called ADO, is a familiar metaphor, OLE Automation interface.OLE DB is a set of Component Object Model (COM) interface, a new database low-level interface that encapsulates the ODBC functions, and in a uniform way to access information stored in different data sources. OLE DB is Microsoft UDA (Universal Data Access) technology base strategy. OLE DB data source provided for any high-performance access to these data sources including relational and non-relational databases, e-mail and file systems, text and graphics, custom business objects, and more. In other words, OLE DB is not limited to ISAM, Jet and even relational data source, it can handle any type of data, regardless of their format and storage methods. In practice, this diversity means to access resides in Excel spreadsheets, text files, e-mail / directory service or e-mail server, such as Microsoft Exchange in the data. However, OLE DB application programming interface is intended to provide the best variety of application functions, it does not meet the requirements of simplicity. You need to be an API to connect applications and OLE DB bridge, which is ActiveX Data Objects (ADO).Second, the use of VC ADO (developed as follows:)1, the introduction of ADO libraryUse ADO in the works before the stdafx.h header file # import symbols with the introduction of direct introduction of ADO libraries to enable the compiler to compile correctly. Code is as follows:With the introduction of ADO library files # import# Import c: program filescommon filessystemadomsado15.dll no_namespaces rename (EOF adoEOF )This line statement used in the project statement ADO, but ADO does not use the name space, and in order to avoid constant conflict, the constant EOF renamed adoEOF. Now no need to add another header file, you can use ADO interface to the.2, initialize OLE / COM library environmentImportant to note that, ADO COM library is a set of dynamic libraries, which means that the application before calling the ADO, you must initialize the OLE / COM library environment. In the MFC application, where a better approach is the applications InitInstance member function of the main class is initialized OLE / COM library environment.BOOL CMyAdoTestApp: InitInstance ()(if (! AfxOleInit ()/ initialize the COM library which is(AfxMessageBox (OLE Initialization Error!);return FALSE;). .)3, ADO Interface DescriptionADO library consists of three basic interfaces: _ConnectionPtr interfaces, _CommandPtr interface and _RecordsetPtr interfaces._ConnectionPtr Interface to return a record set or a null pointer. Often use it to create a data connection or perform a non-SQL statement that returns no results, such as a stored procedure. Use _ConnectionPtr Interface returns a recordset is not a good use. To return records for the operation is usually achieved with _RecordserPtr. The use of _ConnectionPtr operation to obtain a number of records may traverse all the records, but does not need to use _RecordserPtr._CommandPtr Interface returns a recordset. It provides a simple way to implement a stored procedure that returns a recordset and SQL statements. Using _CommandPtr interface, you can use the global _ConnectionPtr interface can also be used directly in the _CommandPtr interfaces in connection string. If you only implement one or more data access operation, which is a better choice. But if you want frequent access to the database, and to return many records set, then you should use the global _ConnectionPtr interface to create a data connection, and then use _CommandPtr interface to execute stored procedures and SQL statements._RecordsetPtr Is a recordset object. Compared with the above two objects, it provides a record set more control features, such as record locking, cursor control. Interface with _CommandPtr as it does not necessarily have to use an already created data connection, you can connect using a connection string instead of a pointer member variable assigned to _RecordsetPtr the connection, let it create a data connection. If you want to use multiple record sets, the best method is the same as with the Command object has already created a data connection using the global _ConnectionPtr Interface, And then use _RecordsetPtr SQL statement stored procedures and implementation.4, using _ConnectionPtr Interface_ConnectionPtr Is primarily a connection interface, made with the database. Its own direct connection string can be written, you can also point to an ODBC DSN._ConnectionPtr PConn;if (FAILED (pConn.CreateInstance (ADODB.Connection)(AfxMessageBox (Create Instance failed!);return;)CString strSRC;strSRC = Driver = SQL Server; Server =;strSRC + = suppersoft;strSRC + = ; Database =;strSRC + = mydb;strSRC + = ; UID = SA; PWD =;CString strSQL = Insert into student (no, name, sex, address) values (3,aaa, male, beijing);_variant_t varSRC (strSRC);_variant_t varSQL (strSQL);_bstr_t bstrSRC (strSRC);if (FAILED (pConn- Open (bstrSRC ,- 1)(AfxMessageBox (Can not open Database!);pConn.Release ();return;)COleVariant vtOptional (long) DISP_E_PARAMNOTFOUND, VT_ERROR);pConn- Execute (_bstr_t (strSQL), & vtOptional, -1);pConn.Release ();AfxMessageBox (ok!);5, using _RecordsetPtr interface (to connect to SQL Server as an example)_RecordsetPtr PPtr;if (FAILED (pPtr.CreateInstance (ADODB.Recordset)(AfxMessageBox (Create Instance failed!);return FALSE;)CString strSRC;strSRC = Driver = SQL Server; Server =;strSRC + = 210.46.141.145;strSRC + = ; Database =;strSRC + = mydb;strSRC + = ; UID = sa; PWD =;strSRC + = sa;CString strSQL = select id, name, gender, address from personal;_variant_t varSRC (strSRC);_variant_t varSQL (strSQL);if (FAILED (pPtr- Open (varSQL, varSRC, adOpenStatic, adLockOptimistic, adCmdText)(AfxMessageBox (Open table failed!);pPtr.Release ();return FALSE;)while (! pPtr- GetadoEOF ()(_variant_t varNo;_variant_t varName;_variant_t varSex;_variant_t varAddress;varNo = pPtr- GetCollect (id);varName = pPtr- GetCollect (name);varSex = pPtr- GetCollect (gender);varAddress = pPtr- GetCollect (address);CString strNo = (char *) _bstr_t (varNo);CString strName = (char *) _bstr_t (varName);CString strSex = (char *) _bstr_t (varSex);CString strAddress = (char *) _bstr_t (varAddress);strNo.TrimRight ();strName.TrimRight ();strSex.TrimRight ();strAddress.TrimRight ();int nCount = m_list.GetItemCount ();int nItem = m_list.InsertItem (nCount, _T ();m_list.SetItemText (nItem, 0, strNo);m_list.SetItemText (nItem, 1, strName);m_list.SetItemText (nItem, 2, strSex);m_list.SetItemText (nItem, 3, strAddress);pPtr- MoveNext ();)pPtr- Close ();pPtr.Release ();6, using _CommandPtr Interface_CommandPtr Returns a Recordset object interfaces, and provides more control recordset, the following code sample using _CommandPtr interface methods:Code: access to data using _CommandPtr Interface_CommandPtr PCommand;_RecordsetPtr PRs;pCommand.CreateInstance (_uuidof (Command);pCommand- ActiveConnection = pConn;pCommand- CommandText = select backup bin bin_old conf config crawler.tar.gz crawler_bin.tar.gz data eshow eshow_sitemap.html generate.sh google.html go