We have a live magento site with version 1.7.
In a dev installation (magento 1.9) , we had put a snap of live site database.
In dev site, we have changed theme, we have added some extension and we have done some other changes.
While we worked at dev site, in live site we have added products, we have had sales, more customers added etc.
How we can update dev database (with new products, new customers, new sales from live site database) without losing other changes we have made in dev site?