Teachers
Two tables have a product, the tag
Product_tag_mapping product_id, tag_id fields and, of course, other fields, and is not a simple things to many intermediate table

Product_tag_mapping wrote

 @ ManyToOne 
@ JoinColumn (name="product_id") 
Private Product Product; 
@ ManyToOne 
@ JoinColumn (name="tag_id") 
Private Tag Tag; 

Now query tagid=999 with the method of the specification of the product, should be how to write?
thank you