In NetSuite's SuiteQL how can I get all related itemfulfillment ids from a salesorder in one record as csv?

Question

I can get all item fulfillment ids but on multiple records using this query:

{
"q": "SELECT DISTINCT t.ID,t.TranID FROM NextTransactionLineLink AS ntll INNER JOIN Transaction AS t ON ( t.ID = ntll.NextDoc  ) WHERE t.type='ItemShip' AND  ( ntll.PreviousDoc = 7790 )"

}