style(sql): format sql create

src/bookstore/inventory.py

@@ -9,7 +9,17 @@ class Inventory:
     def __init__(self, db_path: Path) -> None:
         self.conn = sqlite3.connect(db_path)
         self.cursor = self.conn.cursor()
-        self.cursor.execute("CREATE TABLE IF NOT EXISTS Book (title TEXT, author TEXT, isbn TEXT PRIMARY KEY, price REAL, stock INTEGER)")
+        self.cursor.execute(
+            r"""
+            CREATE TABLE IF NOT EXISTS Book (
+                isbn TEXT PRIMARY KEY NOT NULL,
+                title TEXT DEFAULT 'Unknown' NOT NULL,
+                author TEXT DEFAULT 'Unknown' NOT NULL ,
+                price REAL DEFAULT 0 NOT NULL,
+                stock INTEGER DEFAULT 0 NOT NULL
+            )
+            """
+        )
 
     def save(self) -> None:
         """Save `Inventory` to SQLite database."""
@@ -23,7 +33,7 @@ class Inventory:
         """Add `Book` to the `Inventory`. `Book`s ISBN must be unique."""
         for book in books:
             try:
-                self.cursor.execute("INSERT INTO Book VALUES (?, ?, ?, ?, ?)", (book.title, book.author, book.isbn, book.price, book.stock))
+                self.cursor.execute("INSERT INTO Book VALUES (?, ?, ?, ?, ?)", (book.isbn, book.title, book.author, book.price, book.stock))
                 self.conn.commit()
             except sqlite3.InternalError:
                 print(f"A book with ISBN {book.isbn} already exists in the database.")