How do I change the default "Title" column in SharePoint 2013 into a column which have sequence number generate automatically?
Example as below:
PO-15-2001 PO-15-2002 PO-15-2003
No need for separate tables keeping track of a unique number, the ID value is unique.
But you can not use it in a calculated column directly so you need one Workflow to write the item ID to another column
You can then use a Calculated column
="PO-" & TEXT( [Created] , "yy" ) & "2" & TEXT( [MyID] , "000" )
If you really want this in your Title column you have to add this string building to your first Workflow and set the Title field
If you need more fancy stuff:
You will need a workflow.
Step 1 - create a table with 1 item to keep track of the unique number (200x) (can also record any other information needed as well here)
Step 2 - create the workflow that gets that item's value and sets the Title field to PO-15-[Number]. Update the current number in the other list by incrementing it by 1 (or any other logic you have).
Step 3 - Profit.
Conversely you can use the ID number of the item it's self although be aware you can not edit the ID.