I have a document library, where I have few properties to add, like name, title, type, project number etc.

For Example if the project Numbers are ABC, DEF, GHI etc.

As of now the unique document ID appears as below:

ABC/01 where ABC is project Name and 01 is the unique ID which sharepoint generates.

Now, when I add a second document related to a different project DEF. The ID becomes DEF/02.

Is it possible to generate a number DEF/01? If not using ID column, is there any other tools which will enable me to auto number the items based on the column value.

You can do that with workflows. Create a metadata column for the project (ideally using something like document sets so the 'project level' metadata is synchronised) and then a workflow that adds that project tag and the document ID number.

It might be possible to do it with a calculated column but i don't think it's that powerful.

You can do with the below

1)A workflow as stated above

2)Calulated columne,created new column in list and state the forumula

3)Event receivers,in itemadded event form your own formula and update the field of the item

If you want to auto number the unique ID column for each project number(e.g. abc/01, abc/02, def/01), in logic, when new item is saved into library, we have to get the maximum number by retrieving all existing item ID for one particualr project, then plus one, using event receivers should be more flexible.

More information for your reference.

https://msdn.microsoft.com/en-us/library/ff398052.aspx

http://sharepointsimple.blogspot.com/2009/04/itemadding-vs-itemadded.html

https://msdn.microsoft.com/en-us/library/office/ee534956%28v=office.14%29.aspx?f=255&MSPPError=-2147217396

Thanks

Daniel