Pull operations of SQL Server CE

Extracted from the EVC advanced programming and application development book, we can use hresult hR = noerror;
Isscerda * pcerda = NULL;
BSTR = NULL;
BSTR bconnectstr = NULL;
BSTR bquerystr = NULL;
BSTR blocalconnectstr = NULL;
BSTR blocaltablename = NULL;
BSTR berrortablename = NULL;
Rda_trackoption trackoption = trackingoff; HR = coinitializeex (null, coinit_multithreaded); // You must initialize the COM interface first.
HR = cocreateinstance (clsid_remotedataaccess, null, clsctx_inproc_server, iid_isscerda, (lpvoid *) & pcerda );
Assert (hR = s_ OK );
Assert (pcerda! = NULL );
 
// Set the Internet URL
BSTR = sysallocstring (_ T ("http: // host address/virtual path/sscesaw.dll"); // The host address must use an IP address instead of a computer name.
Pcerda-> put_interneturl (BSTR );
Sysfreestring (BSTR); // set Internet Username
BSTR = sysallocstring (_ T (""));
Pcerda-> put_internetlogin (BSTR );
Sysfreestring (BSTR); // sets the internet password
BSTR = sysallocstring (_ T (""));
Pcerda-> put_internetpassword (BSTR );
Sysfreestring (BSTR); trackoption = trackingoff; // set the name of the error table.
Berrortablename = sysallocstring (_ T ("tblerrors "));

// Set the server connection string
Bconnectstr = sysallocstring (_ T ("provider = sqloledb; Data Source = Host address; initial catalog = database name; user id = sa; Password = 123 ")); // It is best to set SQL Server to the mode of SQL Server and Windows mutual authentication and set a password
 
// Set the connection string of the local database
Blocalconnectstr = sysallocstring (_ T ("provider = Microsoft. sqlserver. oledb. ce.2.0; Data Source = // database name on my documents // PDA. SDF "); // The first-mover event first creates an empty database on isqlw20.exe installed on PDA. Do not create a table; otherwise, an error occurs. It is recommended that you check whether the suffix SDF exists after creation.
Pcerda-> put_localconnectionstring (blocalconnectstr );
Sysfreestring (BSTR );

// Set the local table name
Blocaltablename = sysallocstring (local table name); // This table must not exist beforehand. Otherwise, an error occurs.

// 9. Set the query SQL statement
Bquerystr = sysallocstring (_ T ("select * from table name on SQL Server "));
// Obtain server data
HR = pcerda-> pull (blocaltablename, bquerystr, bconnectstr, trackoption, berrortablename );

Sysfreestring (blocaltablename );
Sysfreestring (bquerystr );
Sysfreestring (bconnectstr );
Sysfreestring (berrortablename );

If (succeeded (HR ))
{
Afxmessagebox (_ T ("OK "));
}
Else
{
Issceerrors * pissceerrors = NULL;
If (succeeded (hR = pcerda-> get_errorrecords (& pissceerrors )))
{
Showerrors (pissceerrors); // This is an easy-to-find error, which is listed below
Pissceerrors-> release ();
}
}
// Release the remote access interface
 
Pcerda-> release (); void showerrors (issceerrors * pissceerrors)
{
Hresult hr;
Long cbbuf;
Long I;
Long lerrorcount;
Long lerrorindex;
Long lparamcount;
Long lparamindex;
Variant var;
Variant varparam;
Wchar wszbuff [4096];
Wchar * pwszbuffpos = & wszbuff [0];
BSTR;
Issceerror * pissceerror = NULL;
Issceparams * pissceparams = NULL;
Issceparam * pissceparam = NULL;
Bool fsuccess = false;
 
// Initialize the variable
Variantinit (& var );
Variantinit (& varparam );
 
// Obtain the number of errors through the iissceerrors Interface
If (failed (hR = pissceerrors-> get_count (& lerrorcount )))
Goto exit;
If (lerrorcount <= 0)
{
: MessageBox (null, l "no error message", l "Display error", mb_ OK );
Fsuccess = true;
Goto exit;
}
 
// Use the pop-up dialog box to display each error.
For (lerrorindex = 0; lerrorindex <lerrorcount; lerrorindex ++)
{
Cbbuf = swprintf (pwszbuffpos, l "error % d of % d/R/N ",
Lerrorindex + 1, lerrorcount );
Pwszbuffpos + = cbbuf;

// Get error records
Var. Vt = vt_i4;
Var. lval = lerrorindex;
If (failed (hR = pissceerrors-> get_item (VAR, & pissceerror) goto exit;

// Get error details
If (failed (hR = pissceerror-> get_description (& BSTR) goto exit;
Cbbuf = swprintf (pwszbuffpos, l "Description: '% s'/R/N", BSTR );
Pwszbuffpos + = cbbuf;
Sysfreestring (BSTR );

// Error message number
If (failed (hR = pissceerror-> get_number (& I) goto exit;
Cbbuf = swprintf (pwszbuffpos, l "number: % 8.8x/R/N", I );
Pwszbuffpos + = cbbuf;

// Local error
If (failed (hR = pissceerror-> get_nativeerror (& I) goto exit;
Cbbuf = swprintf (pwszbuffpos, l "native_error: % d/R/N", I );
Pwszbuffpos + = cbbuf;

// Get the error source
If (failed (hR = pissceerror-> get_source (& BSTR) goto exit;
Cbbuf = swprintf (pwszbuffpos, l "Source: '% s'/R/N", BSTR );
Pwszbuffpos + = cbbuf;
Sysfreestring (BSTR );

// Get error parameter information
If (failed (hR = pissceerror-> get_params (& pissceparams) goto exit;

// Obtain the number of Error Parameters
If (failed (hR = pissceparams-> get_count (& lparamcount) goto exit;

// Display each parameter
For (lparamindex = 0; lparamindex <lparamcount; lparamindex ++)
{

// Get the error parameter object
Var. Vt = vt_i4;
Var. lval = lparamindex;
If (failed (hR = pissceparams-> get_item (VAR, & pissceparam) goto exit;

// Get and display the error parameter value
If (failed (hR = pissceparam-> get_param (& varparam) goto exit;
If (vt_i4 = varparam. vt | vt_ui4 = varparam. Vt)
{
Cbbuf = swprintf (pwszbuffpos, l "P % d: % d/R/N", lparamindex,
(Long) varparam. lval );
}
Else if (vt_i2 = varparam. vt | vt_ui2 = varparam. Vt)
{
Cbbuf = swprintf (pwszbuffpos, l "P % d: % d/R/N", lparamindex,
(Long) varparam. ival );
}
Else if (vt_bstr = varparam. Vt)
{
Cbbuf = swprintf (pwszbuffpos, l "P % d: '% s'/R/N", lparamindex,
Varparam. bstrval );
}
Pwszbuffpos + = cbbuf;

// Clear parameter variables
Variantclear (& varparam );

// Release the parameter object
Pissceparam-> release ();
Pissceparam = NULL;
}
Cbbuf = swprintf (pwszbuffpos, l "/R/N ");
Pwszbuffpos + = cbbuf;

}
 
// Use the pop-up box to display the error message
: MessageBox (null, wszbuff, l "error", mb_ OK );
Fsuccess = true;
 
Exit:
// Release the error parameter object
If (pissceparam)
{
Pissceparam-> release ();
Pissceparam = NULL;
}
 
// Release the error parameter set object
If (pissceparams)
{
Pissceparams-> release ();
Pissceparams = NULL;
}
 
// Release the error object
If (pissceerror)
{
Pissceerror-> release ();
Pissceerror = NULL;
}
 
// If an error message fails to be obtained
If (! Fsuccess)
{
: MessageBox (null, l "failed to get error message! ", L" Display error ", mb_ OK );
}
Return;
}