In that diagram, the books_authors table is *clearly* a MANY-TO-MANY table. Why would you ever think it is one-to-many??? The same ISBN can have many authorID values. The same authorID can have many ISBN values. That is the *definition* of a many-to-many table.
The name 160Credits@.60each is using THREE illegal characters:
(a) It starts with a digit.
(b) It contains @
(c) It contains .
If you really MUST use a name like that (why???) then you will HAVE to *ALWAYS* put back tick marks around it in EVERY usage: `160Credits@.60each`
For the life of me, though, I don't know why you would want to name a field like that.
An optimist sees the glass as half full.
A pessimist sees the glass as half empty.
A realist drinks it no matter how much there is.