Insert only selected field with multiple value into one value with delimiter

I have two tables, one is to record the queue, another one is record the data for each queue

Queue Table

Id	Queue_Id
1	1

Data Table

Id	Queue_Id	Item	Field
1	1	A	Vege
2	1	B	Fruit
3	1	A	Vege
4	1	B	Fruit

Now I have to create a stored procedure that will return a temp table in below format

Queue_Id	Item	Field
1	A	Vege, Fruit
1	B	Vege, Fruit

If I SELECT using String_AGG(), the Queue_Id will be also returning like this Queue_Id = (1,1), but I just want it to display only Queue_Id = (1)

Answer

You can use group by as follows:

Select d.queue_id, d.item,
       Max(Select String_agg(field,',') within group (order by field) 
          from (Select distinct field 
                  from data dd where dd.queue_id = d.queue_id) t) t ) as fields
  From data d
  Join queue q on d.queue_id = q.queue_id
 Where q.id = 1
 Group by queue_id, item