sqlite 3.4 updating table with data from different table - changed with 3.3 - newbie question
You need to gove sqllite the chance to know which column from which table you mean
UPDATE GULLfromLG
   SET issbn = (
   SELECT issbn
  FROM BIBinfo
 WHERE bibno = GULLfromLG.bibno)
[Example](http://sqlfiddle.com/#!5/c6687/1)