Firebird: som van die vermenigvuldiging van twee velde binne 'n geselekteerde verklaring

Question

Wat ek nodig het, is om die som van die vermenigvuldiging van twee velde te kry.

Byvoorbeeld: SUM ((field_1 or field_2) * field_3)

Maar field_1 of field_2 word gekies op grond van die waarde van 'n vierde veld, field_4

My tafel:

field_1: Float
field_2: Float
field_3: Float
field_4: Char

Kortom, wat ek nodig het, is so iets:

SELECT
...
IF field_4 = 'K'
THEN
    SUM( field_1 * field_3 )
ELSE
    SUM( field_2 * field_3 )

Ek het probeer met IF- en saakverklarings, maar ek kan dit nie laat werk nie. Hier my regte navraag:

SELECT  
    D.id,
    D.name,
    SUM(CASE WHEN D.sale_unity = 'K' 
        THEN (D.cost_price * CI.quantity_k)
        ELSE (D.cost_price * CI.quantity_u) ) AS total_cost,
    SUM(CASE WHEN D.sale_unity = 'K' 
        THEN (D.sale_price * CI.quantity_k)
        ELSE (D.sale_price * CI.quantity_u) ) AS net
FROM DETAIL D
INNER JOIN VOUCHER AS V ON V.id = D.voucher_id
WHERE V.client_id = 97 AND V.date BETWEEN '06/01/2012' AND '07/01/2012'
GROUP BY D.id, D.name 

Answer 1

Ek dink dat wat verkeerd is met u navraag, is dat u saakverklaring die einde ontbreek. Probeer hierdie:

SELECT  
    D.id,
    D.name,
    SUM(CASE WHEN D.sale_unity = 'K' 
        THEN (D.cost_price * CI.quantity_k)
        ELSE (D.cost_price * CI.quantity_u) END ) AS total_cost,
    SUM(CASE WHEN D.sale_unity = 'K' 
        THEN (D.sale_price * CI.quantity_k)
        ELSE (D.sale_price * CI.quantity_u) END ) AS net
FROM DETAIL D
INNER JOIN VOUCHER AS V ON V.id = D.voucher_id
WHERE V.client_id = 97 AND V.date BETWEEN '06/01/2012' AND '07/01/2012'
GROUP BY D.id, D.name