left join mysql where clause code example

Example: use of where in left join in mysql

SELECT bk1.book_name,bk1.isbn_no,bk1.book_price,bk1.pub_lang         
FROM  book_mast bk1          
LEFT JOIN book_mast bk2 ON bk1.book_price<bk2.book_price        
WHERE bk2.pub_lang='German';