C++使用OLEDB连接SQL Server

Windows环境中使用OLEDB连接SQL Server，本文只作为对前两篇博文的补充，并非推荐做法。

下面例子依次调用了：

• 初始化环境
• 连接SQL Server
• 执行查询
• 关闭连接

示例代码：
oledbTest.cpp

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1. #include "stdafx.h"
   
2. #include <windows.h>
   
3. #include <sys\timeb.h>
   
4. #include <time.h>
   
5. #include <stdio.h>
   
6. #include <iostream>
   
7. #include <map>
   
8. #include <atldbcli.h>
   
9. #include <atlconv.h>
   
10. using namespace std;
    
11.  
    
12. typedef struct result
    
13. {
    
14.     char ename[19];
    
15.     char cname[100];
    
16.     DBSTATUS dwEnameStatus;
    
17.     DBSTATUS dwCnameStatus;
    
18. } RESULT;
    
19.  
    
20. int _tmain(int argc, _TCHAR* argv[])
    
21. {
    
22.     HRESULT hr;
    
23.     CDataSource m_ds;
    
24.     CSession m_session;
    
25.  
    
26.     //连接串指定数据库，用户名，密码
    
27.     char szConnectionString[512] = "Provider=SQLNCLI10.1;Data Source=10.2.0.10;Initial Catalog=MYDB;User ID=user;Password=passwd;Application Name=SQLSERVER;MARS Connection=True";
    
28.  
    
29.     ::CoInitialize(NULL);
    
30.  
    
31.     //连接数据库
    
32.     hr = m_ds.OpenFromInitializationString(CA2W(szConnectionString));
    
33.     
    
34.     //打开会话
    
35.     hr = m_session.Open(m_ds);
    
36. 
    
37.     DBORDINAL ulColumns = 0;
    
38.     CDBPropSet dbPropSet(DBPROPSET_ROWSET);
    
39.     CCommand<CManualAccessor, CRowset, CNoMultipleResults> m_command;
    
40.     hr = m_command.CreateCommand(m_session);
    
41.  
    
42.     CComPtr<ICommandText> spCommandText;
    
43.     hr = m_command.m_spCommand->QueryInterface(&spCommandText);
    
44.     USES_CONVERSION;
    
45.     
    
46.     //查询语句
    
47.     const TCHAR *cmd = _T(" select col1, col2 from table1 ");
    
48.  
    
49.     hr = spCommandText->SetCommandText(DBGUID_SQL, T2COLE(cmd));
    
50.  
    
51.     dbPropSet.AddProperty(DBPROP_ISequentialStream, true);
    
52.  
    
53.     hr = m_command.Open(&dbPropSet, NULL, false);
    
54.  
    
55.     DBCOLUMNINFO *m_pColumnInfo;
    
56.     LPOLESTR m_pStrings;
    
57.  
    
58.     //获取列信息
    
59.     hr = m_command.GetColumnInfo(&ulColumns
    
60.         , &m_pColumnInfo
    
61.         , &m_pStrings);
    
62.  
    
63.     BYTE * m_pRowInfoBuff;
    
64.     
    
65.     //初始化列绑定字段
    
66.     DBCOUNTITEM cbRowSize = (m_pColumnInfo[0].ulColumnSize + 1) * sizeof(CHAR);
    
67.     DBCOUNTITEM cbRowSize2 = (m_pColumnInfo[1].ulColumnSize + 1) * sizeof(CHAR);
    
68.  
    
69.     RESULT rst;
    
70.  
    
71.     int bufferSize = sizeof(rst.ename) + sizeof(rst.cname) +1;
    
72.     m_pRowInfoBuff = new BYTE[bufferSize];
    
73.  
    
74.     hr = m_command.CreateAccessor(ulColumns, m_pRowInfoBuff, (DBLENGTH)bufferSize);
    
75.  
    
76.     //DBORDINAL* pLength = (DBORDINAL*)(m_pRowInfoBuff + cbRowSize);
    
77.     //DBSTATUS* pStatus = (DBSTATUS*)(m_pRowInfoBuff + cbRowSize);
    
78.     DBTYPE dbType=DBTYPE_STR;
    
79.     DBLENGTH dbLength = (m_pColumnInfo[0].ulColumnSize + 1) * sizeof(TCHAR);
    
80.     DBLENGTH dbLength2 = (m_pColumnInfo[1].ulColumnSize + 1) * sizeof(TCHAR);
    
81.  
    
82.     //m_command.AddBindEntry(1, dbType, dbLength, pValue, pLength, pStatus);
    
83.     m_command.AddBindEntry(1, dbType, dbLength, rst.ename, NULL, &rst.dwEnameStatus);
    
84.     m_command.AddBindEntry(2, dbType, dbLength2, rst.cname, NULL, &rst.dwCnameStatus);
    
85.  
    
86.     hr = m_command.Bind();
    
87.  
    
88.     //获取查询信息
    
89.     while(S_OK == m_command.MoveNext())
    
90.     {
    
91.         printf(" ename = [%s] ,cname = [%s]\n", rst.ename, rst.cname);
    
92.     }
    
93.  
    
94.     //关闭连接
    
95.     m_command.Close();
    
96.     m_session.Close();
    
97.     m_ds.Close();
    
98.  
    
99.     ::CoUninitialize();
    
100.  
     
101.     ::getchar();
     
102.  
     
103. }