issuing-a-parameterized-query.md

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Learn more about: Issuing a Parameterized Query	Issuing a Parameterized Query	10/19/2018	parameter queries, running using CCommand class	aedb0fce-52a4-4c97-a5c9-b2114be6c3b0

Issuing a Parameterized Query

The following 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 following code, in an ATL project, uses the CCommand class instead of the CTable class used in the previous example, Traversing a Simple Rowset.

#include <atldbcli.h>
#include <iostream>

using namespace std;

int main()
{
    CDataSource connection;
    CSession session;
    CCommand<CAccessor<CArtists>> artists;
    LPCSTR clsid; // Initialize CLSID_MSDASQL here
    LPCTSTR pName = L"NWind";

    // Open the connection, session, and table, specifying authentication
    // using Windows NT integrated security. Hard-coding a password is a major
    // security weakness.
    connection.Open(clsid, pName, NULL, NULL, DBPROP_AUTH_INTEGRATED);

    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;
    }

    return 0;
}

The user record, CArtists, looks like this example:

class CArtists
{
public:
// Data Elements
   CHAR m_szFirstName[20];
   CHAR m_szLastName[30];
   short m_nAge;

// Column 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)
   SET_PARAM_TYPE(DBPARAMIO_INPUT)
   COLUMN_ENTRY(1, m_nAge)
END_PARAM_MAP()
};

See also

Working with OLE DB Consumer Templates