Kasus MySQL/Jika/Lalu

Saya kira maksud Anda jika stock > 1000 lalu warna lain not green .

SELECT  Beer.Beer, 
        Beer.Brewery, 
        Beer.Style, 
        Beer.ABV, 
        Beer.Hops, 
        Beer.SRM,
        Sum(BeerStock.Quantity) totalQuantity,
        CASE WHEN Sum(BeerStock.Quantity) < 0 THEN ''
            WHEN Sum(BeerStock.Quantity) BETWEEN 0 AND 999 THEN 'Red'
            WHEN Sum(BeerStock.Quantity) BETWEEN 1000 AND 4999 THEN 'Yellow'
            WHEN Sum(BeerStock.Quantity) BETWEEN 5000 AND 9999 THEN 'GREEN'
            WHEN Sum(BeerStock.Quantity) >= 10000 THEN 'Another Color' 
        END
FROM    Beer
        INNER JOIN BeerStock
            ON Beer.Beer = BeerStock.Beer
-- Where    ..other conditions..

tetapi jika Anda benar-benar bersungguh-sungguh,

SELECT  Beer.Beer, 
        Beer.Brewery, 
        Beer.Style, 
        Beer.ABV, 
        Beer.Hops, 
        Beer.SRM,
        Sum(BeerStock.Quantity) totalQuantity,
        CASE WHEN Sum(BeerStock.Quantity) < 0 THEN ''
            WHEN Sum(BeerStock.Quantity) BETWEEN 0 AND 999 THEN 'Red'
            WHEN Sum(BeerStock.Quantity) BETWEEN 1000 AND 4999 THEN 'Yellow'
            WHEN Sum(BeerStock.Quantity) >= 5000 THEN 'GREEN'
        END
FROM    Beer
        INNER JOIN BeerStock
            ON Beer.Beer = BeerStock.Beer
-- Where    ..other conditions..

Satu hal lagi, Anda juga perlu menggunakan GROUP BY klausa atau Anda hanya akan mengembalikan satu catatan meskipun Anda memiliki catatan yang berbeda,

SELECT  Beer.Beer, 
        Beer.Brewery, 
        Beer.Style, 
        Beer.ABV, 
        Beer.Hops, 
        Beer.SRM,
        Sum(BeerStock.Quantity) totalQuantity,
        CASE WHEN Sum(BeerStock.Quantity) < 0 THEN ''
            WHEN Sum(BeerStock.Quantity) BETWEEN 0 AND 999 THEN 'Red'
            WHEN Sum(BeerStock.Quantity) BETWEEN 1000 AND 4999 THEN 'Yellow'
            WHEN Sum(BeerStock.Quantity) BETWEEN 5000 AND 9999 THEN 'GREEN'
            WHEN Sum(BeerStock.Quantity) >= 10000 THEN 'Another Color' 
        END
FROM    Beer
        INNER JOIN BeerStock
            ON Beer.Beer = BeerStock.Beer
-- Where    ..other conditions..
GROUP   BY Beer.Beer, 
        Beer.Brewery, 
        Beer.Style, 
        Beer.ABV, 
        Beer.Hops, 
        Beer.SRM