We not only created a lot of new categories, we deleted a lot of old categories and renamed some of them as well. Now the issue was to correctly assigning products to appropriate categories. We were provided product csv with three columns (category,sku,category-code). category-code was for SAP admins, so they can update their inventory according to code. But we need other two columns only. Here is the shell script I wrote which runs smoothly and does the work for me :-)
Some of our simple products were not correctly assigned to a configurable product. And, some of them were visible independently in the front end. My task was to assign simple products to correct configurable product and make associated products to not visible individually. It was easy to find configurable product and associated simple products because of the SKU they had. All simple products had sku configurableSKU__*.
We got a new magento project which was developed by another web development company and it wasn't finished. Client didn't have admin details but he had FTP details. He didn't know about control panel url, so couldn't access phpMyadmin. Instead of going back and forth with client about details, I wrote this code, so I could create admin user myself and access the admin.
I think it will be a good idea to create new admin user for every single admin user including developers, so if one developer quits we can just delete the user and don't need to worry about changing passwords again and again.