Use ADO in VC)

(From http://www.j2megame.org/wupei/blog.php/myblog/vc/2007/07/21/vc-ado-access)

Using ADO to directly access the ACCESS database under VC does not require users to establish ODBC data sources)

1. Include the relevant dynamic link library

1. // Add the last part in stdafx. H (Note: Make sure it is in the last part; otherwise, compilation errors will occur)
2. # Import "C:/program files/common files/system/ADO/msado15.dll" no_namespace Rename ("EOF", "adoeof ")

2. Connection creation and initialization

1. // Related member variables
2. _ Connectionptr m_conn;
3. _ Recordsetptr m_res;
4.  
5. // Member function block (generally written in cdocment class constructor)
6. Try
7. {
8. Coinitialize (null );
9. M_conn.createinstance (_ uuidof (connection ));
10. Cstring strfilename;
11. Strfilename = "mybase. mdb"; // Add the file name of your database. The editing status should be in the directory of the source file.
12. M_conn-> open ("provider = Microsoft. Jet. oledb.4.0; Data Source =" + strfilename,
13. "", "", Adconnectunspecified); // user name, password
14. M_res.createinstance (_ uuidof (recordset ));
15. }
16. Catch (_ com_error e) // exception detection
17. {
18. Afxmessagebox ("database connection error! ", Mb_iconexclamation );
19. Exit (0); // The program exits due to an error.
20. }

3. Database-related operations (there are many operation methods, and only one simple operation is provided here)
Assume that the database table is designed as follows:
Table Name: mytable
Table Design:
Automatic ID
String type name
Bool type sex

(1) Increase

1. _ Variant_t m_resa; // It can be declared as a member variable.
2.  
3. Cstring strmyname = "myname ";
4. Cstring strsex = "true ";
5.  
6. Cstring SQL;
7. SQL = "insert into mytable (name, sex )";
8. SQL + = "values ('" + strmyname + "',";
9. SQL + = "" + strsex + "";
10. SQL + = ")";
11.  
12. Try
13. {
14. M_conn-> execute (_ bstr_t) SQL, & m_resa, ad1_text); // execute the "add" Operation
15. }
16. Catch (_ com_error E)
17. {
18. Afxmessagebox ("database addition error", mb_iconexclamation );
19. Exit (0); // The program exits due to an error.
20. }

(2) Delete

1. _ Variant_t m_resa; // It can be declared as a member variable.
2.  
3. Cstring Strid = "1"; // ID of the record to be deleted
4. Cstring SQL;
5.  
6. SQL = "delete from mytable"; // note that spaces are required
7. SQL + = "where id =" + Strid; // other syntaxes for detailed query of SQL statements
8.  
9. Try
10. {
11. M_conn-> execute (_ bstr_t) SQL, & m_resa, ad1_text); // execute the "add" Operation
12. }
13. Catch (_ com_error E)
14. {
15. Afxmessagebox ("database deletion error", mb_iconexclamation );
16. Exit (0); // The program exits due to an error.
17. }

(3) Change

1. _ Variant_t m_resa; // It can be declared as a member variable.
2.  
3. Cstring SQL;
4. Cstring strmyname = "myname ";
5. Cstring strsex = "true ";
6. Cstring Strid = "1"; // ID of the record to be updated
7.  
8. SQL = "Update mytable set ";
9. SQL + = "name = '" + strmyname + "',";
10. SQL + = "Sex =" + strsex + "";
11. SQL + = "where id =" + Strid;
12.  
13. Try
14. {
15. M_conn-> execute (_ bstr_t) SQL, & m_resa, ad1_text); // execute the "add" Operation
16. }
17. Catch (_ com_error E)
18. {
19. Afxmessagebox ("database deletion error", mb_iconexclamation );
20. Exit (0); // The program exits due to an error.
21. }

(4) Query

1. _ Variant_t m_resa; // It can be declared as a member variable.
2. Cstring SQL;
3. SQL = "select * From mytable"; // the query statement changes, and the following statement also changes.
4.  
5. // # Include <afxtempl. h> // Add the header file.
6. // Carray <cmyclass, cmyclass &> m_array; // use a container to save the data you have obtained.
7.  
8. Try
9. {
10. M_res = m_conn-> execute (_ bstr_t) SQL, & m_resa, ad1_text );
11. }
12. Catch (_ com_error E)
13. {
14. Afxmessagebox ("database query error", mb_iconexclamation );
15. Exit (0 );
16. }
17.  
18. // M_array.removeall (); // clear the container
19.  
20. Try
21. {
22. While (! M_res-> adoeof) // looping records
23. {
24. _ Variant_t vid, vname, vsex;
26. Vid = m_res-> getcollect ("ID ");
27. Vname = m_res-> getcollect ("name ");
28. Vsex = m_res-> getcollect ("sex ");
30. //////////////////////////////////////// ///////
31. Int NID;
32. Nid = (long) vid. lval;
33. //////////////////////////////////////// ///////
34. Cstring strname;
35. If (vt_null! = Vname. Vt) // if the data is not empty
36. {
37. Strname = (lpctstr) vname. bstrval;
38. }
39. //////////////////////////////////////// ///////
40. Bool bsex;
41. If (vt_null! = Vsex. Vt)
42. {
43. Bsex = (bool) vsex. boolval;
44. }
45. //////////////////////////////////////// ////////
47. // Cmyclass one (NID, strname, bsex); // create a Data Object
48. // M_array.add (one); // Add an array
50. M_res-> movenext (); // move to the next record
51. }
52. }
53. Catch (_ com_error E)
54. {
55. Afxmessagebox ("database query error", mb_iconexclamation );
56. Exit (0 );
57. }

4. Shut down the database

1. Try
2. {
3. If (m_res! = NULL)
4. {
5. M_res-> close (); // close the record set
6. }
7. If (m_conn! = NULL)
8. {
9. M_conn-> close (); // close the connection
10. }
11. }
12. Catch (_ com_error E)
13. {
14. Afxmessagebox ("database disconnection error", mb_iconexclamation );
15. Exit (0 );
16. }

5. Summary
Database Operations are diverse. You can check the relevant information.
Here, we only introduce a simple operation. We can encapsulate the object and directly call it.