Firebird SQL IF在哪里

Firebird SQL IF in where

我想从(库存)架子1和架子2的产品中选择数量，还要从架子3中列出项目，但将架子3的数量列出为数量= 0。

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SELECT item, amount
FROM prodcuts
WHERE kind = 'bike'
AND (stock = 'shelf1' OR stock = 'shelf2' )

。

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TABLE products
item kind stock amount
cruiser bike shelf1 1
cruiser bike shelf2 2
racing bike shelf3 4

结果为

cruiser 3

但是我需要结果

1 2	cruiser 3 racing 0

您的结果似乎是：

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SELECT p.item, SUM(CASE WHEN p.stock = 'shelf3' THEN 0 ELSE p.amount END)
FROM products p
GROUP BY p.item;

但是，我不太确定这与您的解释是否相符。