Firebird SQL：由于合并，查询速度较慢，或者可以重写查询

我对一个常用的查询有一些性能问题

SELECT
v.id,
coalesce((SELECT sum(amount) FROM artjournal WHERE variant_ref=v.id AND storage_ref=1 AND atype_ref in (1,3,4)), 0) "fv", 
coalesce((SELECT sum(amount) FROM artjournal WHERE variant_ref=v.id AND storage_ref=1 AND atype_ref=2), 0) "ivo", 
coalesce((SELECT sum(amount) FROM artjournal WHERE variant_ref=v.id AND storage_ref=1 AND atype_ref=5), 0) "iio", 
coalesce((SELECT sum(amount * mvalue) FROM artjournal WHERE variant_ref=v.id AND storage_ref=1), 0) "vw"
FROM productvariant v

由于artjournal是一个大表，每天都有数千条新记录，因此性能变得非常糟糕

我在所有ID字段上都有索引

有没有办法重写这句话来加快速度？或者我可以使用不同的方法从artjournal表检索数据，如果结果为null，则返回0吗

谢谢你的想法

---

Christiaan

看起来您需要一个经过筛选的聚合：

SELECT v.id,
       sum(case when a.atype_ref in (1,3,4) then a.amount else 0 end) as "fv",
       sum(case when a.atype_ref = 2 then a.amount else 0 end) as "ivo",
       sum(case when a.atype_ref = 5 then a.amount else 0 end) as "iio",
       sum(a.amount * a.mvalue) as "vw"
FROM productvariant v
  LEFT JOIN artjournal a ON a.variant_ref = v.id
WHERE storage_ref = 1
GROUP BY v.id;

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仍然缺少

coalesce

s，因为如果设置为

sum

的记录为

NULL

，则结果也是如此。