I want to auto-fill (column A) with different set of data. The details of which are mentioned in the excel attached. Kindly provide me a solution for it.
If I understood correctly, you want to populate the empty cells in A with the Project # until it changes and continue with new project #.
If so, simply apply filter to A and select to view only the empty cells... A2 should remain visible. In A2, input "=A1" and Enter. Drag down to fill all cells until there is no ore data in B. This will only fill the cells that are visible so the Project # already there will remain untouched.
Remove filters and it should look like the attached file.