Database

select Q.ID, Q.item, Q.vendor, Q.Quote, V.phone, V.fax
from (
  select ID, item, min(quote) AS MinQuote
  from quote_tb
  where ID = 11
  group by ID, item
) AS MinQ
inner join quote_tb Q
  on Q.ID = MinQ.ID
  and Q.item = MinQ.item
  and Q.quote = MinQ.quote
inner join vendor_tb AS V
  on V.name = Q.vendor
order by Q.ID, Q.item

...
from (
  select Q.ID, Q.item, min(vendor) AS MinVendor
  from (
    select ID, item, min(quote) AS MinQuote
    from quote_tb
    where ID = 11
    group by ID, item
  ) AS MinQ
  inner join quote_tb AS Q
    on Q.ID = MinQ.ID
    and Q.item = MinQ.item
    and Q.quote = MinQ.quote
  group by Q.ID, Q.item
) AS MinS
inner join quote_tb Q
  on Q.ID = MinS.ID
  and Q.item = MinS.item
  and Q.vendor = MinS.MinVendor
...

SELECT f.item, f.vendor, f.quote, v.phone, v.fax
	FROM (SELECT item, min(quote) AS minprice FROM quote_tb WHERE ID='11' GROUP BY item) 
	AS x INNER JOIN quote_tb AS f ON f.item = x.item AND f.quote = x.minprice
        inner join vendor_tb as v on f.vendor = v.name

SELECT f.item, f.vendor, f.quote, v.phone, v.fax
	FROM ((SELECT item, min(quote) AS minprice FROM quote_tb WHERE ID='11' GROUP BY item) 
	AS x INNER JOIN quote_tb AS f ON f.item = x.item AND f.quote = x.minprice)
        inner join vendor_tb as v on f.vendor = v.name

1. Make sure you have proper indexes on your tables.
   
2. Look at using some inner (or outer) joins, depending on what data you are trying to return.
   

tonyong wrote:

I am not sure of the indexes on the tables as this is a company database and I am actually a student on attachment and the company ask me to try this

SELECT ppar_engparameters.parmval, ppar_engparameters.parmname,
    prcd.prcdname||' '||prcd.prcdversion, prcd.activeflag,
    prcd.prodstatis, catg_pll.catnumber, catg_pll.category
FROM ppar_engparameters
INNER JOIN prcd
  ON prcd.prcdname = ppar_engparameters.prcdname
  AND prcd.activeflag = 'A'
LEFT OUTER JOIN catg_pll
  ON catg_pll.partprcdname = prcd.prcdname
  AND catg_pll.partprcdversion  = prcd.prcdversion
WHERE ppar_engparameters.parmval= 'MyValue'

--For the link from product-parameter to product.
create unique index prcd_idx1 on prcd (prcdname, prcdversion)
--For the link from product.
create index catg_pll_idx1 on catg_pll (partprcdname, partprcdversion)
--For the search on parameter values.
create index ppar_engparameters_idx1 on ppar_engparameters
     (parmval, activeflag)