Bagaimana saya bisa mengubah kueri ini dengan dua Gabung Dalam sehingga berhenti memberikan hasil duplikat?

Tanpa melihat contoh outputnya, sulit dikatakan. Tetapi apakah Anda sudah mencoba kueri yang sama persis dengan DISTINCT sederhana? ditambahkan ke SELECT ?

SELECT DISTINCT itpitems.identifier, itpitems.name, itpitems.subtitle, itpitems.description, itpitems.itemimg, itpitems.mainprice, itpitems.upc, itpitems.isbn, itpitems.weight, itpitems.pages, itpitems.publisher, itpitems.medium_abbr, itpitems.medium_desc, itpitems.series_abbr, itpitems.series_desc, itpitems.voicing_desc, itpitems.pianolevel_desc, itpitems.bandgrade_desc, itpitems.category_code, itprank.overall_ranking, itpitnam.name AS artist, itpitnam.type_code 
FROM itpitems 
INNER JOIN itprank ON ( itprank.item_number = itpitems.identifier ) 
INNER JOIN itpitnam ON ( itpitems.identifier = itpitnam.item_number ) 
WHERE mainprice >1