OCCI(Oracle C++ Call Interface) Example to Query the Data from a Table

The following Example demonestrate how to Query a Table Using OCCI(Oracle Caller C++ Interface). 
I have created an Employees Class with one Method queryEmployees to Query the data. Details are givene below. 

Class Declaration Section

I have defined a file named Employees.h which contains the Employees Class declaration 

1. #ifndef _EMPLOYEES_H  
2. #define _EMPLOYEES_H  
3. #include <occi.h>  
4. #include <iostream>  
5. #include <iomanip>  
6. using namespace oracle::occi;  
7. using namespace std;  
8.   
9. class Employees {  
10.     public:  
11.         Employees();  
12.         virtual ~Employees();  
13.         void queryEmployees();  
14.     private:  
15.         Environment *env;  
16.         Connection *con;  
17.         ResultSet *rs;  
18.         string user;  
19.         string passwd;  
20.         string db;  
21. };  
22. #endif

Class Definition Sectionbelow. 

1. #include "Employees.h"  
2. #include <occi.h>  
3. #include <stdlib.h>  
4. using namespace std;  
5. using namespace oracle::occi;  
6.   
7.   
8. Employees::Employees() {  
9.         user = "hr";  
10.         passwd = "**";  
11.         db = "192.168.*.*:1521/noncdb";  
12.   
13.         env = Environment::createEnvironment(Environment::DEFAULT);  
14.   
15.         try  
16.         {  
17.                 con = env->createConnection(user, passwd, db);  
18.         }  
19.         catch (SQLException& ex)  
20.         {  
21.                 cout << ex.getMessage();  
22.                 exit(EXIT_FAILURE);  
23.         }  
24. }  
25.   
26. Employees::~Employees()         {  
27.          env->terminateConnection(con);  
28.          Environment::terminateEnvironment (env);  
29. }  
30. void Employees::queryEmployees()  
31. {  
32.   
33.         Statement *stmt = NULL;  
34.         ResultSet *rs = NULL;  
35.         string sql = "SELECT employee_id, first_name, last_name FROM employees WHERE rownum<=50 ORDER BY employee_id";  
36.   
37.         try  
38.         {  
39.                 stmt = con->createStatement(sql);  
40.         }  
41.         catch (SQLException& ex)  
42.         {  
43.                 cout << ex.getMessage();  
44.         }  
45.         if (stmt)  
46.         {  
47.                 try  
48.                 {  
49.                         stmt->setPrefetchRowCount(32);  
50.                         rs = stmt->executeQuery();  
51.                 }  
52.                 catch (SQLException& ex)  
53.                 {  
54.                         cout << ex.getMessage();  
55.                 }  
56.                 if (rs)  
57.                 {  
58.                         cout << endl << setw(8) << left << "ID"  
59.                         << setw(22) << left << "FIRST NAME"  
60.                         << setw(27) << left << "LAST NAME"  
61.                         << endl;  
62.                         cout << setw(8) << left << "******"  
63.                         << setw(22) << left << "********************"  
64.                         << setw(27) << left << "*************************"  
65.                         << endl;  
66.                         while (rs->next()) {  
67.                                 cout << setw(8) << left << rs->getString(1)  
68.                                 << setw(22) << left << (rs->isNull(2) ? "n/a" : rs->getString(2))  
69.                                 << setw(27) << left << rs->getString(3)  
70.                                 << endl;  
71.                         }  
72.                         cout << endl;  
73.                         stmt->closeResultSet(rs);  
74.                 }  
75.                 con->terminateStatement(stmt);  
76.         }  
77. }  

Define the Main Program that calls the queryEmployees Method.

1. #include "Employees.h"  
2. #include <occi.h> 
3. int main (void) {  
4.           Employees *pEmployees = new Employees();  
5.           pEmployees->queryEmployees();  
6.           delete pEmployees;  
7.           return 0;  
8.   }  

To compile the above program either makefile utility can be used or enter the following command. 

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1. g++ -c Employees.cpp -I/opt/ora12c/product/12.1.0/dbhome_1/rdbms/public/ -L/opt/ora12c/product/12.1.0/dbhome_1/lib/
2. 
   
3. g++ -c EmployeesMain.cpp -I/opt/ora12c/product/12.1.0/dbhome_1/rdbms/public/ -L/opt/ora12c/product/12.1.0/dbhome_1/lib/
4. 
   
5. g++  EmployeesMain.o Employees.o -o Employees  -I/opt/ora12c/product/12.1.0/dbhome_1/rdbms/public/ -L/opt/ora12c/product/12.1.0/dbhome_1/lib/ -lclntsh -locci

It will generate an executable file named Employees.

1. execute the program by typing the below command.  
2. ./Employees  
3.   
4. -------------  
5. Output  
6. -------------  
7. ID      FIRST NAME            LAST NAME  
8. ******  ********************  *************************  
9. 100     Steven                King  
10. 101     Neena                 Kochhar  
11. 102     Lex                   De Haan  
12. 103     Alexander             Hunold  
13. 104     Bruce                 Ernst  
14. 105     David                 Austin  
15. 106     Valli                 Pataballa  
16. 107     Diana                 Lorentz  
17. 108     Nancy                 Greenberg  
18. 109     Daniel                Faviet  
19. 110     John                  Chen  
20. 111     Ismael                Sciarra  
21. 112     Jose Manuel           Urman  
22. 113     Luis                  Popp  
23. 114     Den                   Raphaely  
24. 115     Alexander             Khoo  
25. 116     Shelli                Baida  
26. 117     Sigal                 Tobias  
27. 118     Guy                   Himuro  
28. 119     Karen                 Colmenares  
29. 120     Matthew               Weiss  
30. 121     Adam                  Fripp  
31. 122     Payam                 Kaufling  
32. 123     Shanta                Vollman  
33. 124     Kevin                 Mourgos  
34. 125     Julia                 Nayer  
35. 126     Irene                 Mikkilineni  
36. 127     James                 Landry  
37. 128     Steven                Markle  
38. 129     Laura                 Bissot  
39. 130     Mozhe                 Atkinson  
40. 131     James                 Marlow  
41. 132     TJ                    Olson  
42. 133     Jason                 Mallin  
43. 134     Michael               Rogers  
44. 135     Ki                    Gee  
45. 136     Hazel                 Philtanker  
46. 137     Renske                Ladwig  
47. 138     Stephen               Stiles  
48. 139     John                  Seo  
49. 140     Joshua                Patel  
50. 141     Trenna                Rajs  
51. 142     Curtis                Davies  
52. 143     Randall               Matos  
53. 144     Peter                 Vargas  
54. 145     John                  Russell  
55. 146     Karen                 Partners  
56. 147     Alberto               Errazuriz  
57. 148     Gerald                Cambrault  
58. 149     Eleni                 Zlotkey