Gunakan Driver Visual FoxPro ODBC dengan Aplikasi C atau Visual C++ Anda

Aplikasi C atau C++ Anda berkomunikasi dengan data Visual FoxPro dengan mengirim pernyataan SQLExecute atau SQLExecDirect ke Visual FoxPro. Pernyataan ini dapat berisi yang berikut:

Untuk informasi selengkapnya tentang SQL asli visual FoxPro, lihat dokumentasi Visual FoxPro.

Contoh: Menggunakan Driver Visual FoxPro ODBC dengan Aplikasi C atau C++ Anda

Contoh berikut menggunakan ODBC C API untuk mengambil data yang disimpan di bidang last_name dalam tabel karyawan dalam database sampel Microsoft® Visual FoxPro bernama TasTrade. Database ini disediakan dengan Visual FoxPro dan diinstal secara default di lokasi berikut:

c:\vfp\samples\mainsamp\data\tastrade.dbc

Contoh menampilkan satu nama belakang pada satu waktu, memungkinkan Anda mengklik OK pada kotak pesan untuk melihat nama belakang berikutnya. Diasumsikan bahwa sumber data bernama Tastrade telah disiapkan untuk menggunakan database Tastrade.dbc.

Catatan

Pemeriksaan kesalahan harus dilakukan pada semua panggilan API ODBC; contoh ini mengecualikan pemeriksaan kesalahan demi keringkasan.

// FoxPro_ODBC_Driver_with_C.cpp  
// compile with: odbc32.lib user32.lib /c  
#include <windows.h>  
#include <sql.h>  
#include <sqlext.h>  
#include <stdio.h>  
#include <mbstring.h>  
  
#define MAX_DATA 100  
#define MYSQLSUCCESS(rc) ((rc==SQL_SUCCESS)||(rc==SQL_SUCCESS_WITH_INFO))  
  
class direxec {  
   RETCODE rc;        // ODBC return code  
   HENV henv;         // Environment     
   HDBC hdbc;         // Connection handle  
   HSTMT hstmt;       // Statement handle  
   unsigned char szData[MAX_DATA];   // Returned data storage  
   SDWORD cbData;     // Output length of data  
   unsigned char chr_ds_name[SQL_MAX_DSN_LENGTH];   // Data source name  
  
public:  
   direxec();           // Constructor  
   void sqlconn();      // Allocate env, stat, and conn  
   void sqlexec(unsigned char *);   // Execute SQL statement  
   void sqldisconn();   // Free pointers to env, stat, conn, and disconnect  
   void error_out();    // Displays errors  
};  
  
// Constructor initializes the string chr_ds_name with the data source name.  
direxec::direxec() {  
   _mbscpy_s(chr_ds_name, (const unsigned char *)"tastrade");  
}  
  
// Allocate environment handle, allocate connection handle,  
// connect to data source, and allocate statement handle.  
void direxec::sqlconn() {  
   SQLAllocEnv(&henv);  
   SQLAllocConnect(henv, &hdbc);  
   rc=SQLConnect(hdbc, chr_ds_name, SQL_NTS, NULL, 0, NULL, 0);  
  
   // Deallocate handles, display error message, and exit.  
   if (!MYSQLSUCCESS(rc)) {  
      SQLFreeEnv(henv);  
      SQLFreeConnect(hdbc);  
      error_out();  
      exit(-1);  
   }  
  
   rc = SQLAllocStmt(hdbc, &hstmt);  
}  
  
// Execute SQL command with SQLExecDirect() ODBC API.  
void direxec::sqlexec(unsigned char * cmdstr) {  
   rc = SQLExecDirect(hstmt, cmdstr, SQL_NTS);  
   if (!MYSQLSUCCESS(rc)) {   // Error  
      error_out();  
      // Deallocate handles and disconnect.  
      SQLFreeStmt(hstmt, SQL_DROP);  
      SQLDisconnect(hdbc);  
      SQLFreeConnect(hdbc);  
      SQLFreeEnv(henv);  
      exit(-1);  
   }  
   else {  
      for (rc = SQLFetch(hstmt) ; rc == SQL_SUCCESS; rc=SQLFetch(hstmt)) {  
         SQLGetData(hstmt, 1, SQL_C_CHAR, szData, sizeof(szData), &cbData);  
         // In this example, the data is returned in a messagebox for  
         // simplicity. However, normally the SQLBindCol() ODBC API could  
         // be called to bind individual data rows and assign for a rowset.  
         MessageBox(NULL, (const char *)szData, "ODBC", MB_OK);  
      }  
   }  
}  
  
// Free the statement handle, disconnect, free the connection handle, and  
// free the environment handle.  
void direxec::sqldisconn() {  
   SQLFreeStmt(hstmt, SQL_DROP);  
   SQLDisconnect(hdbc);  
   SQLFreeConnect(hdbc);  
   SQLFreeEnv(henv);  
}  
  
// Display error message in a message box that has an OK button.  
void direxec::error_out() {  
   unsigned char szSQLSTATE[10];  
   SDWORD nErr;  
   unsigned char msg[SQL_MAX_MESSAGE_LENGTH + 1];  
   SWORD cbmsg;  
  
   while(SQLError(0, 0, hstmt, szSQLSTATE, &nErr, msg, sizeof(msg), &cbmsg) == SQL_SUCCESS) {  
      sprintf_s((char *)szData, MAX_DATA, "Error:\nSQLSTATE=%s, Native error=%ld, msg='%s'",   
         szSQLSTATE, nErr, msg);  
  
      MessageBox(NULL, (const char *)szData, "ODBC Error", MB_OK);  
   }  
}  
  
int main (){  
   // Declare an instance of the direxec object.  
   direxec x;  
  
   // Allocate handles and connect.  
   x.sqlconn();  
  
   // Execute SQL command "SELECT last_name FROM employee".  
   x.sqlexec((UCHAR FAR *)"SELECT last_name FROM employee");  
  
   // Free handles, and disconnect.  
   x.sqldisconn();  
  
   // Return success code; example executed successfully.  
   return (TRUE);  
}