SELECT Item.item_id, Item.seller_id, Item.title, Item.description, Item.current_price, Item.increment, Item.picture, Item.category_id, Derived.item_id AS Expr1 
FROM (Item 
  INNER JOIN (
    SELECT DISTINCT item_id 
    FROM Keyword
    WHERE (keyword LIKE '%' + ? + '%')
  ) Derived 
  ON Derived.item_id = Item.item_id
)