update method
Implementation
Future<void> update(ISQLiteItem item) async {
final db = await getOpenDatabase();
final map = item.toMap();
final tableName = item.getTableName();
var existingColumns = await tableColumns(tableName, db: db);
map.removeWhere((key, value) => !existingColumns.contains(key));
final id = map[item.getPrimaryKeyName()];
if (id != null && id > 0) {
await db.update(tableName, map,
where: '${item.getPrimaryKeyName()} = ?', whereArgs: [id]);
}
}