Could you tell me how to write in statements for zendselect ()?

Ask how to write the in statement $ sales_id = implode (',', $ sales_id); // echo & nbsp; $ sale_id has a value of 4, 6, 7, 8, 9, 10 $ select & nbsp ;=& nbsp; $ db-& gt; select (); $ select-& gt; ask about how to write in statements about zend select ().
$ Sales_id = implode (',', $ sales_id );
// The echo $ sale_id value is 4, 6, 7, 8, 9, 10.
$ Select = $ db-> select ();
$ Select-> from (TB_PRODUCT ,'*');
// $ Select-> where (TB_PRODUCT. ". sales_id IN ('. $ sales_id .')");
// This sentence has an error. all fields in the search results are sales_id => 0
$ Select-> where (TB_PRODUCT. ". sales_id IN ('4', '6', '7', '8', '9', '10 ')");
// This sentence is correct
$ Select-> order (TB_PRODUCT. '. sales_id DESC ');
$ Product_list = $ db-> fetchAll ($ select );

I would like to ask, how can I write this sentence in red to make the search result the same as the following sentence?
Thank you first.
------ Solution --------------------
$ Select-> where (TB_PRODUCT. ". sales_id IN ($ sales_id )");