Q:

c.fetchall returns nonetype

I have this piece of code that's supposed to select all columns from a table "BTSFinal" where -PCode- is equal to the user's entry -Product_Codev-, insert it into another table -BTSTempt- and select the smallest ID number from it.
                    c.execute("UPDATE BTSTempt SET ID=(SELECT ID FROM BTSFinal WHERE PCode = ?)",(int(Product_Codev.get()),))
                    c.execute("UPDATE BTSTempt SET Date_in=(SELECT Date_in FROM BTSFinal WHERE PCode = ?)",(int(Product_Codev.get()),))
                    c.execute("UPDATE BTSTempt SET PCode=(SELECT PCode FROM BTSFinal WHERE PCode = ?)",(int(Product_Codev.get()),))
                    c.execute("UPDATE BTSTempt SET PName=(SELECT PName FROM BTSFinal WHERE PCode = ?)",(int(Product_Codev.get()),)) 
                    c.execute("UPDATE BTSTempt SET Inc_Price=(SELECT Inc_Price FROM BTSFinal WHERE PCode = ?)",(int(Product_Codev.get()),))
                    c.execute("UPDATE BTSTempt SET Quantity_In=(SELECT Quantity_In FROM BTSFinal WHERE PCode = ?)",(int(Product_Codev.get()),))
                    c.execute("UPDATE BTSTempt SET Outg_Price=(SELECT Outg_Price FROM BTSFinal WHERE PCode = ?)",(int(Product_Codev.get()),))
                    c.execute("UPDATE BTSTempt SET Quantity_Out=(SELECT Quantity_Out FROM BTSFinal WHERE PCode = ?)",(int(Product_Codev.get()),))
                    c.execute("UPDATE BTSTempt SET Description=(SELECT Description FROM BTSFinal WHERE PCode = ?)",(int(Product_Codev.get()),))
                    c.execute("SELECT MIN(ID) FROM BTSTempt")
                    Minid = c.fetchall()[-1]
                    Minidpre = Minid[0]
                    MinimumID=int(Minidpre)

But what I understood from this error 
MinimumID=int(Minidpre)
TypeError: int() argument must be a string, a bytes-like object or a number, not 'NoneType'

Is that there's no match between the "BTSFinal" table in the "PCode" column and the entry which is not the case and I'm absolutely sure that there are matches 
Here's the -BTSFinal- table scheme

ID INTEGER PRIMARYKEY
Date_in TEXT
PCode INTEGER
PName TEXT
Inc_Price INTEGER
Quantity_In INTEGER
Outg_Price INTEGER
Quantity_Out INTEGER
Description TEXT

and the scheme of -BTSTempt- is identical to it.
But it always gives me this error that says the -BTSTempt- table is empty which is indeed the case when I try to open it through a sql viewer
Thank you very much and hope my question is clear.

A:

Whether this "there's no match between the "BTSFinal" table in the "PCode" column" is true is one possiblity. An other possibility is that there is no BTSTemp row to update.  That seems more likely. Perhaps the first UPDATE should actually be an INSERT. 
With only the knowledge of what is posted in the question (which is to say no knowledge of what else the BTSTemp table will be used for), an easier way to get the  MIN(ID) might be:
"SELECT MIN(ID) from BTSFinal where Pcode = ?)"

