在SQL Server數據庫中，C++可以使用ODBC（Open Database Connectivity）接口來進行事務處理。以下是一個簡單的示例代碼，演示如何在C++中使用ODBC接口來執行SQL事務處理：

#include <windows.h>
#include <sql.h>
#include <sqlext.h>
#include <iostream>

int main() {
    SQLHENV henv;
    SQLHDBC hdbc;
    SQLHSTMT hstmt;
    SQLRETURN retcode;

    // Allocate environment handle
    retcode = SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &henv);
    if (retcode != SQL_SUCCESS && retcode != SQL_SUCCESS_WITH_INFO) {
        std::cerr << "Error allocating environment handle" << std::endl;
        return -1;
    }

    // Set ODBC version
    retcode = SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION, (SQLPOINTER) SQL_OV_ODBC3, 0);
    if (retcode != SQL_SUCCESS && retcode != SQL_SUCCESS_WITH_INFO) {
        std::cerr << "Error setting ODBC version" << std::endl;
        return -1;
    }

    // Allocate connection handle
    retcode = SQLAllocHandle(SQL_HANDLE_DBC, henv, &hdbc);
    if (retcode != SQL_SUCCESS && retcode != SQL_SUCCESS_WITH_INFO) {
        std::cerr << "Error allocating connection handle" << std::endl;
        return -1;
    }

    // Connect to database
    retcode = SQLConnect(hdbc, (SQLCHAR*)"YOUR_DSN", SQL_NTS, (SQLCHAR*)"USERNAME", SQL_NTS, (SQLCHAR*)"PASSWORD", SQL_NTS);
    if (retcode != SQL_SUCCESS && retcode != SQL_SUCCESS_WITH_INFO) {
        std::cerr << "Error connecting to database" << std::endl;
        return -1;
    }

    // Allocate statement handle
    retcode = SQLAllocHandle(SQL_HANDLE_STMT, hdbc, &hstmt);
    if (retcode != SQL_SUCCESS && retcode != SQL_SUCCESS_WITH_INFO) {
        std::cerr << "Error allocating statement handle" << std::endl;
        return -1;
    }

    // Begin transaction
    retcode = SQLEndTran(SQL_HANDLE_DBC, hdbc, SQL_COMMIT);
    if (retcode != SQL_SUCCESS && retcode != SQL_SUCCESS_WITH_INFO) {
        std::cerr << "Error beginning transaction" << std::endl;
        return -1;
    }

    // Execute SQL statements within the transaction
    retcode = SQLExecDirect(hstmt, (SQLCHAR*)"INSERT INTO TABLE_NAME (COLUMN1, COLUMN2) VALUES (VALUE1, VALUE2)", SQL_NTS);
    if (retcode != SQL_SUCCESS && retcode != SQL_SUCCESS_WITH_INFO) {
        std::cerr << "Error executing SQL statement" << std::endl;
        return -1;
    }

    // Commit transaction
    retcode = SQLEndTran(SQL_HANDLE_DBC, hdbc, SQL_COMMIT);
    if (retcode != SQL_SUCCESS && retcode != SQL_SUCCESS_WITH_INFO) {
        std::cerr << "Error committing transaction" << std::endl;
        return -1;
    }

    // Free statement handle
    SQLFreeHandle(SQL_HANDLE_STMT, hstmt);

    // Disconnect from database
    retcode = SQLDisconnect(hdbc);
    if (retcode != SQL_SUCCESS && retcode != SQL_SUCCESS_WITH_INFO) {
        std::cerr << "Error disconnecting from database" << std::endl;
        return -1;
    }

    // Free connection handle
    SQLFreeHandle(SQL_HANDLE_DBC, hdbc);

    // Free environment handle
    SQLFreeHandle(SQL_HANDLE_ENV, henv);

    return 0;
}

在上面的示例中，我們首先分配了環境句柄、連接句柄和語句句柄，然后連接到數據庫，并開始一個事務。接下來執行SQL語句并提交事務。最后釋放句柄并斷開與數據庫的連接。請確保將YOUR_DSN、USERNAME、PASSWORD、TABLE_NAME、COLUMN1、COLUMN2、VALUE1和VALUE2替換為實際的值。

這只是一個簡單的示例，實際情況可能會更復雜。建議參考ODBC文檔和SQL Server的文檔以獲取更多關于ODBC接口和事務處理的信息。