Issuing a Parameterized Query

This example issues a simple parameterized query that retrieves records with an age field (that is greater than 30) from a table in a Microsoft Access database. To support the parameter, the user record must have an additional map. The code uses the CCommand class instead of the CTable class used in the previous example, Traversing a Simple Rowset.

#include <atldbcli.h>

CDataSource connection;
CSession session;
CCommand<CAccessor<CArtists> > artists;
 
connection.Open(CLSID_MSDASQL, "NWind", "sa", "");
session.Open(connection);
 
// Set the parameter for the query
artists.m_nAge = 30;
artists.Open(session, "select * from artists where age > ?");
 
// Get data from the rowset
while (artists.MoveNext() == S_OK)
{
   cout << artists.m_szFirstName;
   cout << artists.m_szLastName;
}

The user record, CArtists, looks like this:

class CArtists
{
public:
// Data Elements
   CHAR m_szFirstName[20];
   CHAR m_szLastName[30];
   short m_nAge;
 
// output binding map
BEGIN_COLUMN_MAP(CArtists)
   COLUMN_ENTRY(1, m_szFirstName)
   COLUMN_ENTRY(2, m_szLastName)
   COLUMN_ENTRY(3, m_nAge)
END_COLUMN_MAP()
 
// parameter binding map
BEGIN_PARAM_MAP(CArtists)
   COLUMN_ENTRY(1, m_nAge)
END_PARAM_MAP
};

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