Auto update stock of books

does this work or you
=INDEX('Book inventory'!$F$2:$F$15,MATCH(Stock!B2&Stock!C2,'Book inventory'!$B$2:$B$15&'Book inventory'!$C$2:$C$15,0))-COUNTIFS('Issue Register'!$B$2:$B$15,Stock!B2,'Issue Register'!$C$2:$C$15,Stock!C2,'Issue Register'!$I$2:$I$15,"")

so
=INDEX('Book inventory'!$F$2:$F$15,MATCH(Stock!B2&Stock!C2,'Book inventory'!$B$2:$B$15&'Book inventory'!$C$2:$C$15,0))
Looks up how many of the book you have in stock inventory

Then
COUNTIFS('Issue Register'!$B$2:$B$15,Stock!B2,'Issue Register'!$C$2:$C$15,Stock!C2,'Issue Register'!$I$2:$I$15,"")
Counts if the book has been issues but the return date is blank

it may get complicated if the real data is more complicated or if the database is Huge

over the xmas period
I will be seeing family for a few days, back on 30th Dec, but may have the odd moment to answers here

So i may not reply now until then - sorry if i have misunderstood - or leave hanging

Hopefully other members will pickup before

you have entered
Essentials of medical physiology Sembulingam in book inventory, which has already been listed

so need to use a SUMIFS()
But are you expecting the Stock sheet to update all the titles etc as a Unique list
you are showing as using excel version 2007 - is that still the case , as with the latest version unique values are much easier to code

2007 has SUMIFS()
=SUMIFS('Book inventory'!$F$2:$F$15, 'Book inventory'!$B$2:$B$15,B3,'Book inventory'!$C$2:$C$15,C3)-COUNTIFS('Issue Register'!$B$2:$B$15,Stock!B3,'Issue Register'!$C$2:$C$15,Stock!C3,'Issue Register'!$I$2:$I$15,"")

But if you want to create the Stock sheet from the inventory sheet, that may be more complicated using arrays to extract unique values of Title & Author, also is just those 2 headings always going to be unique ?


I will be seeing family for a few days, back on 30th Dec

So i may not reply now until then - sorry if i have misunderstood - or leave hanging

Hopefully other members will pickup before

you are welcome