使用C++打印数据库中的所有列

我正在尝试使用以下代码获取数据库中表的所有数据：

const string server   = "localhost";
const string username = "root";
const string password = "";

int main()
{
    sql::Driver *driver; 
        sql::Connection *dbConn; 
        sql::Statement  *stmt;   
        sql::ResultSet  *res;    
    //get a driver to use to connect to the DBMS
    try
    {
        driver = get_driver_instance();
    }
    catch (sql::SQLException e)
    {
        cout << "Could not get a database driver. Error message: " << e.what() << endl;
        system("pause");
        exit(1);
    }

    //connect to the DBMS server
    try
    {
        dbConn = driver->connect(server, username, password);
    }
    catch (sql::SQLException e)
    {
        cout << "Could not connect to database. Error message: " << e.what() << endl;
        system("pause");
        exit(1);
    }

    stmt = dbConn->createStatement(); // Specify which connection the SQL statement should be executed on

    // Try to query the database
    try
    {
        stmt->execute("USE test");  // Select which database to use. Notice that we use "execute" to perform a command.
        res = stmt->executeQuery("SELECT * FROM users");

    }
    catch (sql::SQLException e)
    {
        cout << "SQL error. Error message: " << e.what() << endl;
        system("pause");
        exit(1);
    }

    while (res->next())
    {

        cout << res->getString(1) << endl; //this prints the 1st column      
        cout << res->getString(2) << endl; //This the 2nd column
        cout << res->getString(3) << endl;//This the 3rd column
    }





    // Clean up
    delete res;
    delete stmt;
    delete dbConn;
    //system("pause");
    return 0;
}

---

这将从数据库中进行选择，但一次只打印一列。有没有什么方法可以让我在列上循环，而不仅仅是在行上循环。因此，这里不是使用cout getString2而是使用SQLite获取所有表数据并使用c++迭代结果集的另一个示例：

sqlite3_stmt *selectStmt;    
string query = "select * from aTable";
if ( sqlite3_prepare(db, query.c_str(), -1, &selectStmt, 0 ) == SQLITE_OK ) 
{
    int ctotal = sqlite3_column_count(selectStmt); // Count the Number of Columns in the Table
    int res = 0;
    while ( 1 )         
    {
        res = sqlite3_step(selectStmt); // Execute SQL Statement.
        if ( res == SQLITE_ROW ) 
        {
            for ( int i = 0; i < ctotal; i++ )  // Loop times the number of columns in the table
            {
                string s = (char*)sqlite3_column_text(selectStmt, i);  // Read each Column in the row.
                // print or format the output as you want 
                *table_out_File << s << " " ;
            }
            *table_out_File << endl;
        }

        if ( res == SQLITE_DONE || res==SQLITE_ERROR)    
        {
            *table_out_File << "done " << endl;
            break;
        }    
    }
}

---

什么是ctotal？您的tbleI中的列数更新了我的答案是如何获得的