在MySQL查询中使用If Else语句

Question

我有这个问题：

SELECT IF(book_id=2, 'NTR', if(book_id=5,'CBC', if(book_id=1,'CBC','Repair')) AS   
'STATUS',
COUNT(IF(book_id=2, 'NTR', if(book_id=5,'CBC', if(book_id=1,'CBC','Repair'))) AS 
Total
FROM book_entry AS b
WHERE last_updated=(SELECT last_updated FROM book_entry WHERE book_code=b.book_code ORDER  
BY last_updated DESC) AND (SELECT description FROM book_categori AS c, book_item AS i  
WHERE c.id=i.id AND i_item_code=b.item_code) = "NOVEL" 
GROUP BY IF(book_id=2, 'NTR', if(book_id=5,'CBC', if(book_id=1,'CBC','Repair')))

从这个查询中，我得到了这个结果：

STATUS      BIL
---------------
CBC         70
Repair      58

这不像我想要的那样。我想要的是这样的：

STATUS      BIL
---------------
CBC         70
Repair      58
NTR         0

任何人都可以教我在查询中需要更改的内容以获得该结果吗？