static
int OGR2SQLITEDealWithSpatialColumn(OGRLayer* poLayer,
                                    int iGeomCol,
                                    const LayerDesc& oLayerDesc,
                                    const CPLString& osTableName,
                                    OGRSQLiteDataSource* poSQLiteDS,
                                    sqlite3* hDB,
                                    int bSpatialiteDB,
                                    const std::set<LayerDesc>&
                                        WHEN_SPATIALITE(oSetLayers),
                                    const std::set<CPLString>&
                                        WHEN_SPATIALITE(oSetSpatialIndex)
                                   )
{
    OGRGeomFieldDefn* poGeomField =
        poLayer->GetLayerDefn()->GetGeomFieldDefn(iGeomCol);
    CPLString osGeomColRaw;
    if( iGeomCol == 0 )
        osGeomColRaw = OGR2SQLITE_GetNameForGeometryColumn(poLayer);
    else
        osGeomColRaw = poGeomField->GetNameRef();
    const char* pszGeomColRaw = osGeomColRaw.c_str();

    CPLString osGeomColEscaped(OGRSQLiteEscape(pszGeomColRaw));
    const char* pszGeomColEscaped = osGeomColEscaped.c_str();

    CPLString osLayerNameEscaped(OGRSQLiteEscape(osTableName));
    const char* pszLayerNameEscaped = osLayerNameEscaped.c_str();

    CPLString osIdxNameRaw(CPLSPrintf("idx_%s_%s",
                    oLayerDesc.osLayerName.c_str(), pszGeomColRaw));
    CPLString osIdxNameEscaped(OGRSQLiteEscapeName(osIdxNameRaw));

    /* Make sure that the SRS is injected in spatial_ref_sys */
    OGRSpatialReference* poSRS = poGeomField->GetSpatialRef();
    if( iGeomCol == 0 && poSRS == NULL )
        poSRS = poLayer->GetSpatialRef();
    int nSRSId = poSQLiteDS->GetUndefinedSRID();
    if( poSRS != NULL )
        nSRSId = poSQLiteDS->FetchSRSId(poSRS);

    CPLString osSQL;
#ifdef HAVE_SPATIALITE
    bool bCreateSpatialIndex = false;
#endif
    if( !bSpatialiteDB )
    {
        osSQL.Printf("INSERT INTO geometry_columns (f_table_name, "
                    "f_geometry_column, geometry_format, geometry_type, "
                    "coord_dimension, srid) "
                    "VALUES ('%s','%s','SpatiaLite',%d,%d,%d)",
                    pszLayerNameEscaped,
                    pszGeomColEscaped,
                        (int) wkbFlatten(poLayer->GetGeomType()),
                    wkbHasZ( poLayer->GetGeomType() ) ? 3 : 2,
                    nSRSId);
    }
#ifdef HAVE_SPATIALITE
    else
    {
        /* We detect the need for creating a spatial index by 2 means : */

        /* 1) if there's an explicit reference to a 'idx_layername_geometrycolumn' */
        /*   table in the SQL --> old/traditional way of requesting spatial indices */
        /*   with spatialite. */

        std::set<LayerDesc>::const_iterator oIter2 = oSetLayers.begin();
        for(; oIter2 != oSetLayers.end(); ++oIter2)
        {
            const LayerDesc& oLayerDescIter = *oIter2;
            if( EQUAL(oLayerDescIter.osLayerName, osIdxNameRaw) )
            {
                    bCreateSpatialIndex = true;
                    break;
            }
        }

        /* 2) or if there's a SELECT FROM SpatialIndex WHERE f_table_name = 'layername' */
        if( !bCreateSpatialIndex )
        {
            std::set<CPLString>::const_iterator oIter3 = oSetSpatialIndex.begin();
            for(; oIter3 != oSetSpatialIndex.end(); ++oIter3)
            {
                const CPLString& osNameIter = *oIter3;
                if( EQUAL(osNameIter, oLayerDesc.osLayerName) )
                {
                    bCreateSpatialIndex = true;
                    break;
                }
            }
        }

        if( poSQLiteDS->HasSpatialite4Layout() )
        {
            int nGeomType = poLayer->GetGeomType();
            int nCoordDimension = 2;
            if( wkbHasZ((OGRwkbGeometryType)nGeomType) )
            {
                nGeomType += 1000;
                nCoordDimension = 3;
            }

            osSQL.Printf("INSERT INTO geometry_columns (f_table_name, "
                        "f_geometry_column, geometry_type, coord_dimension, "
                        "srid, spatial_index_enabled) "
                        "VALUES (Lower('%s'),Lower('%s'),%d ,%d ,%d, %d)",
                        pszLayerNameEscaped,
                        pszGeomColEscaped, nGeomType,
                        nCoordDimension,
                        nSRSId, static_cast<int>(bCreateSpatialIndex) );
        }
        else
        {
            const char *pszGeometryType = OGRToOGCGeomType(poLayer->GetGeomType());
            if (pszGeometryType[0] == '\0')
                pszGeometryType = "GEOMETRY";

            osSQL.Printf("INSERT INTO geometry_columns (f_table_name, "
                        "f_geometry_column, type, coord_dimension, "
                        "srid, spatial_index_enabled) "
                        "VALUES ('%s','%s','%s','%s',%d, %d)",
                        pszLayerNameEscaped,
                        pszGeomColEscaped, pszGeometryType,
                        wkbHasZ( poLayer->GetGeomType() ) ? "XYZ" : "XY",
                        nSRSId, static_cast<int>(bCreateSpatialIndex) );
        }
    }
#endif // HAVE_SPATIALITE
    char* pszErrMsg = NULL;
    int rc = sqlite3_exec( hDB, osSQL.c_str(), NULL, NULL, &pszErrMsg );
    if( pszErrMsg != NULL )
    {
        CPLDebug("SQLITE", "%s -> %s", osSQL.c_str(), pszErrMsg);
        sqlite3_free(pszErrMsg);
    }

#ifdef HAVE_SPATIALITE
/* -------------------------------------------------------------------- */
/*      Should we create a spatial index ?.                             */
/* -------------------------------------------------------------------- */
    if( !bSpatialiteDB || !bCreateSpatialIndex )
        return rc == SQLITE_OK;

    CPLDebug("SQLITE", "Create spatial index %s", osIdxNameRaw.c_str());

    /* ENABLE_VIRTUAL_OGR_SPATIAL_INDEX is not defined */
#ifdef ENABLE_VIRTUAL_OGR_SPATIAL_INDEX
    osSQL.Printf("CREATE VIRTUAL TABLE \"%s\" USING "
                    "VirtualOGRSpatialIndex(%d, '%s', pkid, xmin, xmax, ymin, ymax)",
                    osIdxNameEscaped.c_str(),
                    nExtraDS,
                    OGRSQLiteEscape(oLayerDesc.osLayerName).c_str());

    rc = sqlite3_exec( hDB, osSQL.c_str(), NULL, NULL, NULL );
    if( rc != SQLITE_OK )
    {
        CPLDebug( "SQLITE",
                  "Error occurred during spatial index creation : %s",
                  sqlite3_errmsg(hDB));
    }
#else //  ENABLE_VIRTUAL_OGR_SPATIAL_INDEX
    rc = sqlite3_exec( hDB, "BEGIN", NULL, NULL, NULL );

    osSQL.Printf("CREATE VIRTUAL TABLE \"%s\" "
                    "USING rtree(pkid, xmin, xmax, ymin, ymax)",
                    osIdxNameEscaped.c_str());

    if( rc == SQLITE_OK )
        rc = sqlite3_exec( hDB, osSQL.c_str(), NULL, NULL, NULL );

    sqlite3_stmt *hStmt = NULL;
    if( rc == SQLITE_OK )
    {
        const char* pszInsertInto = CPLSPrintf(
            "INSERT INTO \"%s\" (pkid, xmin, xmax, ymin, ymax) "
            "VALUES (?,?,?,?,?)", osIdxNameEscaped.c_str());
        rc = sqlite3_prepare(hDB, pszInsertInto, -1, &hStmt, NULL);
    }

    OGRFeature* poFeature;
    OGREnvelope sEnvelope;
    OGR2SQLITE_IgnoreAllFieldsExceptGeometry(poLayer);
    poLayer->ResetReading();

    while( rc == SQLITE_OK &&
            (poFeature = poLayer->GetNextFeature()) != NULL )
    {
        OGRGeometry* poGeom = poFeature->GetGeometryRef();
        if( poGeom != NULL && !poGeom->IsEmpty() )
        {
            poGeom->getEnvelope(&sEnvelope);
            sqlite3_bind_int64(hStmt, 1,
                                (sqlite3_int64) poFeature->GetFID() );
            sqlite3_bind_double(hStmt, 2, sEnvelope.MinX);
            sqlite3_bind_double(hStmt, 3, sEnvelope.MaxX);
            sqlite3_bind_double(hStmt, 4, sEnvelope.MinY);
            sqlite3_bind_double(hStmt, 5, sEnvelope.MaxY);
            rc = sqlite3_step(hStmt);
            if( rc == SQLITE_OK || rc == SQLITE_DONE )
                rc = sqlite3_reset(hStmt);
        }
        delete poFeature;
    }

    poLayer->SetIgnoredFields(NULL);

    sqlite3_finalize(hStmt);

    if( rc == SQLITE_OK )
        rc = sqlite3_exec( hDB, "COMMIT", NULL, NULL, NULL );
    else
    {
        CPLDebug( "SQLITE",
                  "Error occurred during spatial index creation : %s",
                  sqlite3_errmsg(hDB));
        rc = sqlite3_exec( hDB, "ROLLBACK", NULL, NULL, NULL );
    }
#endif //  ENABLE_VIRTUAL_OGR_SPATIAL_INDEX

#endif // HAVE_SPATIALITE

    return rc == SQLITE_OK;
}
OGRLayer * OGRSQLiteExecuteSQL( OGRDataSource* poDS,
                                const char *pszStatement,
                                OGRGeometry *poSpatialFilter,
                                const char *pszDialect )
{
    char* pszTmpDBName = (char*) CPLMalloc(256);
    sprintf(pszTmpDBName, "/vsimem/ogr2sqlite/temp_%p.db", pszTmpDBName);

    OGRSQLiteDataSource* poSQLiteDS = NULL;
    int nRet;
    int bSpatialiteDB = FALSE;

    CPLString osOldVal;
    const char* pszOldVal = CPLGetConfigOption("OGR_SQLITE_STATIC_VIRTUAL_OGR", NULL);
    if( pszOldVal != NULL )
    {
        osOldVal = pszOldVal;
        pszOldVal = osOldVal.c_str();
    }

/* -------------------------------------------------------------------- */
/*      Create in-memory sqlite/spatialite DB                           */
/* -------------------------------------------------------------------- */

#ifdef HAVE_SPATIALITE

/* -------------------------------------------------------------------- */
/*      Creating an empty spatialite DB (with spatial_ref_sys populated */
/*      has a non-neglectable cost. So at the first attempt, let's make */
/*      one and cache it for later use.                                 */
/* -------------------------------------------------------------------- */
#if 1
    static vsi_l_offset nEmptyDBSize = 0;
    static GByte* pabyEmptyDB = NULL;
    {
        static void* hMutex = NULL;
        CPLMutexHolder oMutexHolder(&hMutex);
        static int bTried = FALSE;
        if( !bTried &&
            CSLTestBoolean(CPLGetConfigOption("OGR_SQLITE_DIALECT_USE_SPATIALITE", "YES")) )
        {
            bTried = TRUE;
            char* pszCachedFilename = (char*) CPLMalloc(256);
            sprintf(pszCachedFilename, "/vsimem/ogr2sqlite/reference_%p.db",pszCachedFilename);
            char** papszOptions = CSLAddString(NULL, "SPATIALITE=YES");
            OGRSQLiteDataSource* poCachedDS = new OGRSQLiteDataSource();
            nRet = poCachedDS->Create( pszCachedFilename, papszOptions );
            CSLDestroy(papszOptions);
            papszOptions = NULL;
            delete poCachedDS;
            if( nRet )
                /* Note: the reference file keeps the ownership of the data, so that */
                /* it gets released with VSICleanupFileManager() */
                pabyEmptyDB = VSIGetMemFileBuffer( pszCachedFilename, &nEmptyDBSize, FALSE );
            CPLFree( pszCachedFilename );
        }
    }

    /* The following configuration option is usefull mostly for debugging/testing */
    if( pabyEmptyDB != NULL && CSLTestBoolean(CPLGetConfigOption("OGR_SQLITE_DIALECT_USE_SPATIALITE", "YES")) )
    {
        GByte* pabyEmptyDBClone = (GByte*)VSIMalloc(nEmptyDBSize);
        if( pabyEmptyDBClone == NULL )
        {
            CPLFree(pszTmpDBName);
            return NULL;
        }
        memcpy(pabyEmptyDBClone, pabyEmptyDB, nEmptyDBSize);
        VSIFCloseL(VSIFileFromMemBuffer( pszTmpDBName, pabyEmptyDBClone, nEmptyDBSize, TRUE ));

        poSQLiteDS = new OGRSQLiteDataSource();
        CPLSetThreadLocalConfigOption("OGR_SQLITE_STATIC_VIRTUAL_OGR", "NO");
        nRet = poSQLiteDS->Open( pszTmpDBName, TRUE );
        CPLSetThreadLocalConfigOption("OGR_SQLITE_STATIC_VIRTUAL_OGR", pszOldVal);
        if( !nRet )
        {
            /* should not happen really ! */
            delete poSQLiteDS;
            VSIUnlink(pszTmpDBName);
            CPLFree(pszTmpDBName);
            return NULL;
        }
        bSpatialiteDB = TRUE;
    }
#else
    /* No caching version */
    poSQLiteDS = new OGRSQLiteDataSource();
    char** papszOptions = CSLAddString(NULL, "SPATIALITE=YES");
    CPLSetThreadLocalConfigOption("OGR_SQLITE_STATIC_VIRTUAL_OGR", "NO");
    nRet = poSQLiteDS->Create( pszTmpDBName, papszOptions );
    CPLSetThreadLocalConfigOption("OGR_SQLITE_STATIC_VIRTUAL_OGR", pszOldVal);
    CSLDestroy(papszOptions);
    papszOptions = NULL;
    if( nRet )
    {
        bSpatialiteDB = TRUE;
    }
#endif

    else
    {
        delete poSQLiteDS;
        poSQLiteDS = NULL;
#else // HAVE_SPATIALITE
    if( TRUE )
    {
#endif // HAVE_SPATIALITE
        poSQLiteDS = new OGRSQLiteDataSource();
        CPLSetThreadLocalConfigOption("OGR_SQLITE_STATIC_VIRTUAL_OGR", "NO");
        nRet = poSQLiteDS->Create( pszTmpDBName, NULL );
        CPLSetThreadLocalConfigOption("OGR_SQLITE_STATIC_VIRTUAL_OGR", pszOldVal);
        if( !nRet )
        {
            delete poSQLiteDS;
            VSIUnlink(pszTmpDBName);
            CPLFree(pszTmpDBName);
            return NULL;
        }
    }

/* -------------------------------------------------------------------- */
/*      Attach the Virtual Table OGR2SQLITE module to it.               */
/* -------------------------------------------------------------------- */
    OGR2SQLITEModule* poModule = OGR2SQLITE_Setup(poDS, poSQLiteDS);
    sqlite3* hDB = poSQLiteDS->GetDB();

/* -------------------------------------------------------------------- */
/*      Analysze the statement to determine which tables will be used.  */
/* -------------------------------------------------------------------- */
    std::set<LayerDesc> oSetLayers;
    std::set<CPLString> oSetSpatialIndex;
    CPLString osModifiedSQL;
    OGR2SQLITEGetPotentialLayerNames(pszStatement, oSetLayers,
                                     oSetSpatialIndex, osModifiedSQL);
    std::set<LayerDesc>::iterator oIter = oSetLayers.begin();

    if( strcmp(pszStatement, osModifiedSQL.c_str()) != 0 )
        CPLDebug("OGR", "Modified SQL: %s", osModifiedSQL.c_str());
    pszStatement = osModifiedSQL.c_str(); /* do not use it anymore */

    int bFoundOGRStyle = ( osModifiedSQL.ifind("OGR_STYLE") != std::string::npos );

/* -------------------------------------------------------------------- */
/*      For each of those tables, create a Virtual Table.               */
/* -------------------------------------------------------------------- */
    for(; oIter != oSetLayers.end(); ++oIter)
    {
        const LayerDesc& oLayerDesc = *oIter;
        /*CPLDebug("OGR", "Layer desc : %s, %s, %s, %s",
                 oLayerDesc.osOriginalStr.c_str(),
                 oLayerDesc.osSubstitutedName.c_str(),
                 oLayerDesc.osDSName.c_str(),
                 oLayerDesc.osLayerName.c_str());*/

        CPLString osSQL;
        OGRLayer* poLayer = NULL;
        CPLString osTableName;
        int nExtraDS;
        if( oLayerDesc.osDSName.size() == 0 )
        {
            poLayer = poDS->GetLayerByName(oLayerDesc.osLayerName);
            /* Might be a false positive (unlikely) */
            if( poLayer == NULL )
                continue;

            osTableName = oLayerDesc.osLayerName;

            nExtraDS = -1;

            osSQL.Printf("CREATE VIRTUAL TABLE \"%s\" USING VirtualOGR(%d,'%s',%d)",
                         OGRSQLiteEscapeName(osTableName).c_str(),
                         nExtraDS,
                         OGRSQLiteEscape(osTableName).c_str(),
                         bFoundOGRStyle);
        }
        else
        {
            OGRDataSource* poOtherDS = (OGRDataSource* )
                OGROpen(oLayerDesc.osDSName, FALSE, NULL);
            if( poOtherDS == NULL )
            {
                CPLError(CE_Failure, CPLE_AppDefined,
                         "Cannot open datasource '%s'",
                         oLayerDesc.osDSName.c_str() );
                delete poSQLiteDS;
                VSIUnlink(pszTmpDBName);
                CPLFree(pszTmpDBName);
                return NULL;
            }
            
            poLayer = poOtherDS->GetLayerByName(oLayerDesc.osLayerName);
            if( poLayer == NULL )
            {
                CPLError(CE_Failure, CPLE_AppDefined,
                         "Cannot find layer '%s' in '%s'",
                         oLayerDesc.osLayerName.c_str(),
                         oLayerDesc.osDSName.c_str() );
                delete poOtherDS;
                delete poSQLiteDS;
                VSIUnlink(pszTmpDBName);
                CPLFree(pszTmpDBName);
                return NULL;
            }

            osTableName = oLayerDesc.osSubstitutedName;

            nExtraDS = OGR2SQLITE_AddExtraDS(poModule, poOtherDS);

            osSQL.Printf("CREATE VIRTUAL TABLE \"%s\" USING VirtualOGR(%d,'%s',%d)",
                         OGRSQLiteEscapeName(osTableName).c_str(),
                         nExtraDS,
                         OGRSQLiteEscape(oLayerDesc.osLayerName).c_str(),
                         bFoundOGRStyle);
        }

        char* pszErrMsg = NULL;
        int rc = sqlite3_exec( hDB, osSQL.c_str(),
                               NULL, NULL, &pszErrMsg );
        if( rc != SQLITE_OK )
        {
            CPLError(CE_Failure, CPLE_AppDefined,
                     "Cannot create virtual table for layer '%s' : %s",
                     osTableName.c_str(), pszErrMsg);
            sqlite3_free(pszErrMsg);
            continue;
        }

        if( poLayer->GetGeomType() == wkbNone )
            continue;

        CPLString osGeomColRaw(OGR2SQLITE_GetNameForGeometryColumn(poLayer));
        const char* pszGeomColRaw = osGeomColRaw.c_str();

        CPLString osGeomColEscaped(OGRSQLiteEscape(pszGeomColRaw));
        const char* pszGeomColEscaped = osGeomColEscaped.c_str();

        CPLString osLayerNameEscaped(OGRSQLiteEscape(osTableName));
        const char* pszLayerNameEscaped = osLayerNameEscaped.c_str();

        CPLString osIdxNameRaw(CPLSPrintf("idx_%s_%s",
                        oLayerDesc.osLayerName.c_str(), pszGeomColRaw));
        CPLString osIdxNameEscaped(OGRSQLiteEscapeName(osIdxNameRaw));

        /* Make sure that the SRS is injected in spatial_ref_sys */
        OGRSpatialReference* poSRS = poLayer->GetSpatialRef();
        int nSRSId = poSQLiteDS->GetUndefinedSRID();
        if( poSRS != NULL )
            nSRSId = poSQLiteDS->FetchSRSId(poSRS);

        int bCreateSpatialIndex = FALSE;
        if( !bSpatialiteDB )
        {
            osSQL.Printf("INSERT INTO geometry_columns (f_table_name, "
                        "f_geometry_column, geometry_format, geometry_type, "
                        "coord_dimension, srid) "
                        "VALUES ('%s','%s','SpatiaLite',%d,%d,%d)",
                        pszLayerNameEscaped,
                        pszGeomColEscaped,
                         (int) wkbFlatten(poLayer->GetGeomType()),
                        ( poLayer->GetGeomType() & wkb25DBit ) ? 3 : 2,
                        nSRSId);
        }
#ifdef HAVE_SPATIALITE
        else
        {
            /* We detect the need for creating a spatial index by 2 means : */

            /* 1) if there's an explicit reference to a 'idx_layername_geometrycolumn' */
            /*   table in the SQL --> old/traditionnal way of requesting spatial indices */
            /*   with spatialite. */

            std::set<LayerDesc>::iterator oIter2 = oSetLayers.begin();
            for(; oIter2 != oSetLayers.end(); ++oIter2)
            {
                const LayerDesc& oLayerDescIter = *oIter2;
                if( EQUAL(oLayerDescIter.osLayerName, osIdxNameRaw) )
                {
                     bCreateSpatialIndex = TRUE;
                     break;
                }
            }

            /* 2) or if there's a SELECT FROM SpatialIndex WHERE f_table_name = 'layername' */
            if( !bCreateSpatialIndex )
            {
                std::set<CPLString>::iterator oIter3 = oSetSpatialIndex.begin();
                for(; oIter3 != oSetSpatialIndex.end(); ++oIter3)
                {
                    const CPLString& osNameIter = *oIter3;
                    if( EQUAL(osNameIter, oLayerDesc.osLayerName) )
                    {
                        bCreateSpatialIndex = TRUE;
                        break;
                    }
                }
            }

            if( poSQLiteDS->HasSpatialite4Layout() )
            {
                int nGeomType = poLayer->GetGeomType();
                int nCoordDimension = 2;
                if( nGeomType & wkb25DBit )
                {
                    nGeomType += 1000;
                    nCoordDimension = 3;
                }

                osSQL.Printf("INSERT INTO geometry_columns (f_table_name, "
                            "f_geometry_column, geometry_type, coord_dimension, "
                            "srid, spatial_index_enabled) "
                            "VALUES ('%s',Lower('%s'),%d ,%d ,%d, %d)",
                            pszLayerNameEscaped,
                            pszGeomColEscaped, nGeomType,
                            nCoordDimension,
                            nSRSId, bCreateSpatialIndex );
            }
            else
            {
                const char *pszGeometryType = OGRToOGCGeomType(poLayer->GetGeomType());
                if (pszGeometryType[0] == '\0')
                    pszGeometryType = "GEOMETRY";

                osSQL.Printf("INSERT INTO geometry_columns (f_table_name, "
                            "f_geometry_column, type, coord_dimension, "
                            "srid, spatial_index_enabled) "
                            "VALUES ('%s','%s','%s','%s',%d, %d)",
                            pszLayerNameEscaped,
                            pszGeomColEscaped, pszGeometryType,
                            ( poLayer->GetGeomType() & wkb25DBit ) ? "XYZ" : "XY",
                            nSRSId, bCreateSpatialIndex );
            }
        }
#endif // HAVE_SPATIALITE
        sqlite3_exec( hDB, osSQL.c_str(), NULL, NULL, NULL );

#ifdef HAVE_SPATIALITE
/* -------------------------------------------------------------------- */
/*      Should we create a spatial index ?.                             */
/* -------------------------------------------------------------------- */
        if( !bSpatialiteDB || !bCreateSpatialIndex )
            continue;

        CPLDebug("SQLITE", "Create spatial index %s", osIdxNameRaw.c_str());

        /* ENABLE_VIRTUAL_OGR_SPATIAL_INDEX is not defined */
#ifdef ENABLE_VIRTUAL_OGR_SPATIAL_INDEX
        osSQL.Printf("CREATE VIRTUAL TABLE \"%s\" USING "
                     "VirtualOGRSpatialIndex(%d, '%s', pkid, xmin, xmax, ymin, ymax)",
                     osIdxNameEscaped.c_str(),
                     nExtraDS,
                     OGRSQLiteEscape(oLayerDesc.osLayerName).c_str());

        rc = sqlite3_exec( hDB, osSQL.c_str(), NULL, NULL, NULL );
        if( rc != SQLITE_OK )
        {
            CPLDebug("SQLITE",
                     "Error occured during spatial index creation : %s",
                     sqlite3_errmsg(hDB));
        }
#else //  ENABLE_VIRTUAL_OGR_SPATIAL_INDEX
        rc = sqlite3_exec( hDB, "BEGIN", NULL, NULL, NULL );

        osSQL.Printf("CREATE VIRTUAL TABLE \"%s\" "
                     "USING rtree(pkid, xmin, xmax, ymin, ymax)",
                      osIdxNameEscaped.c_str());

        if( rc == SQLITE_OK )
            rc = sqlite3_exec( hDB, osSQL.c_str(), NULL, NULL, NULL );

        sqlite3_stmt *hStmt = NULL;
        if( rc == SQLITE_OK )
        {
            const char* pszInsertInto = CPLSPrintf(
                "INSERT INTO \"%s\" (pkid, xmin, xmax, ymin, ymax) "
                "VALUES (?,?,?,?,?)", osIdxNameEscaped.c_str());
            rc = sqlite3_prepare(hDB, pszInsertInto, -1, &hStmt, NULL);
        }

        OGRFeature* poFeature;
        OGREnvelope sEnvelope;
        OGR2SQLITE_IgnoreAllFieldsExceptGeometry(poLayer);
        poLayer->ResetReading();

        while( rc == SQLITE_OK &&
               (poFeature = poLayer->GetNextFeature()) != NULL )
        {
            OGRGeometry* poGeom = poFeature->GetGeometryRef();
            if( poGeom != NULL && !poGeom->IsEmpty() )
            {
                poGeom->getEnvelope(&sEnvelope);
                sqlite3_bind_int64(hStmt, 1,
                                   (sqlite3_int64) poFeature->GetFID() );
                sqlite3_bind_double(hStmt, 2, sEnvelope.MinX);
                sqlite3_bind_double(hStmt, 3, sEnvelope.MaxX);
                sqlite3_bind_double(hStmt, 4, sEnvelope.MinY);
                sqlite3_bind_double(hStmt, 5, sEnvelope.MaxY);
                rc = sqlite3_step(hStmt);
                if( rc == SQLITE_OK || rc == SQLITE_DONE )
                    rc = sqlite3_reset(hStmt);
            }
            delete poFeature;
        }

        poLayer->SetIgnoredFields(NULL);

        sqlite3_finalize(hStmt);

        if( rc == SQLITE_OK )
            rc = sqlite3_exec( hDB, "COMMIT", NULL, NULL, NULL );
        else
        {
            CPLDebug("SQLITE",
                     "Error occured during spatial index creation : %s",
                     sqlite3_errmsg(hDB));
            rc = sqlite3_exec( hDB, "ROLLBACK", NULL, NULL, NULL );
        }
#endif //  ENABLE_VIRTUAL_OGR_SPATIAL_INDEX

#endif // HAVE_SPATIALITE

    }

/* -------------------------------------------------------------------- */
/*      Reload, so that virtual tables are recognized                   */
/* -------------------------------------------------------------------- */
    poSQLiteDS->ReloadLayers();

/* -------------------------------------------------------------------- */
/*      Prepare the statement.                                          */
/* -------------------------------------------------------------------- */
    /* This will speed-up layer creation */
    /* ORDER BY are costly to evaluate and are not necessary to establish */
    /* the layer definition. */
    int bUseStatementForGetNextFeature = TRUE;
    int bEmptyLayer = FALSE;

    sqlite3_stmt *hSQLStmt = NULL;
    int rc = sqlite3_prepare( hDB,
                              pszStatement, strlen(pszStatement),
                              &hSQLStmt, NULL );

    if( rc != SQLITE_OK )
    {
        CPLError( CE_Failure, CPLE_AppDefined,
                "In ExecuteSQL(): sqlite3_prepare(%s):\n  %s",
                pszStatement, sqlite3_errmsg(hDB) );

        if( hSQLStmt != NULL )
        {
            sqlite3_finalize( hSQLStmt );
        }

        delete poSQLiteDS;
        VSIUnlink(pszTmpDBName);
        CPLFree(pszTmpDBName);

        return NULL;
    }

/* -------------------------------------------------------------------- */
/*      Do we get a resultset?                                          */
/* -------------------------------------------------------------------- */
    rc = sqlite3_step( hSQLStmt );
    if( rc != SQLITE_ROW )
    {
        if ( rc != SQLITE_DONE )
        {
            CPLError( CE_Failure, CPLE_AppDefined,
                  "In ExecuteSQL(): sqlite3_step(%s):\n  %s",
                  pszStatement, sqlite3_errmsg(hDB) );

            sqlite3_finalize( hSQLStmt );

            delete poSQLiteDS;
            VSIUnlink(pszTmpDBName);
            CPLFree(pszTmpDBName);

            return NULL;
        }

        if( !EQUALN(pszStatement, "SELECT ", 7) )
        {

            sqlite3_finalize( hSQLStmt );

            delete poSQLiteDS;
            VSIUnlink(pszTmpDBName);
            CPLFree(pszTmpDBName);

            return NULL;
        }

        bUseStatementForGetNextFeature = FALSE;
        bEmptyLayer = TRUE;
    }

/* -------------------------------------------------------------------- */
/*      Create layer.                                                   */
/* -------------------------------------------------------------------- */
    OGRSQLiteSelectLayer *poLayer = NULL;

    poLayer = new OGRSQLiteExecuteSQLLayer( pszTmpDBName,
                                            poSQLiteDS, pszStatement, hSQLStmt,
                                            bUseStatementForGetNextFeature, bEmptyLayer );

    if( poSpatialFilter != NULL )
        poLayer->SetSpatialFilter( poSpatialFilter );

    return poLayer;
}

/************************************************************************/
/*                   OGRSQLiteGetReferencedLayers()                     */
/************************************************************************/

std::set<LayerDesc> OGRSQLiteGetReferencedLayers(const char* pszStatement)
{
/* -------------------------------------------------------------------- */
/*      Analysze the statement to determine which tables will be used.  */
/* -------------------------------------------------------------------- */
    std::set<LayerDesc> oSetLayers;
    std::set<CPLString> oSetSpatialIndex;
    CPLString osModifiedSQL;
    OGR2SQLITEGetPotentialLayerNames(pszStatement, oSetLayers,
                                     oSetSpatialIndex, osModifiedSQL);

    return oSetLayers;
}