SQL SUM Function

[Paris2000]

Hi There, as a new developer I was hoping someone out there could answer this for me.

Is it possible to use the SUM function on a field that has been already SUMmed ?

eg, How would I manage to get the total of the Payments Column in this example.

SELECT DISTINCT
e.description,
SUM(a.hectares) Area,
b.rate,
SUM(a.HECTARES * b.RATE) Payment,
c.occ_id
FROM G_FIELD_AREA_ZONATION a,
G_PAYMENT_RATE b,
G_OCCUPIER c,
G_FIELD d,
G_ZONATION_TYPE e,
G_HOLDING f,
G_SEASON g
WHERE a.znt_id IN (SELECT znt_id FROM G_ZONATION_TYPE)
AND c.occ_id = &Occupier_Id
AND c.occ_id = f.occ_id
AND f.HLD_ID = d.HLD_ID
AND b.sea_id = g.sea_id
AND a.ZNT_ID = e.ZNT_ID
AND d.FLD_ID = a.fld_id
AND e.ZNT_ID = b.ZNT_ID
GROUP BY e.description,b.rate, c.occ_id

Many thanks to any of you who can help.

 

[CD12]

Try:

SELECT SUM( Payment )
FROM (
     SELECT DISTINCT        
            e.description, 
            SUM(a.hectares) Area,
            b.rate,
            SUM(a.HECTARES * b.RATE) Payment,
            c.occ_id
     FROM   G_FIELD_AREA_ZONATION a,
            G_PAYMENT_RATE b,
            G_OCCUPIER c,
            G_FIELD d,
            G_ZONATION_TYPE e,
            G_HOLDING f,
            G_SEASON g
     WHERE  a.znt_id IN (SELECT znt_id FROM G_ZONATION_TYPE)
     AND       c.occ_id = &Occupier_Id
     AND       c.occ_id = f.occ_id
     AND       f.HLD_ID = d.HLD_ID
     AND       b.sea_id = g.sea_id
     AND       a.ZNT_ID = e.ZNT_ID
     AND       d.FLD_ID = a.fld_id
     AND    e.ZNT_ID = b.ZNT_ID
     GROUP BY e.description,b.rate, c.occ_id
);

Does this help?