[英]SQL, Check if Rows are in another Table
我有两张桌子, Stock
和Warehouse
。
我需要获得所有仓库中可用的物品。
这是一个例子:
Stock Table:
ItemID WarehouseID ItemAmount
-------------------------------------------
1043 1 20
1043 2 2
1043 3 16
1043 4 17
1044 1 32
1044 2 12
1044 4 7
1055 2 6
Warehouse Table:
WarehouseID WarehouseName
-------------------------------
1 Name1
2 Name2
3 Name3
4 Name4
对于示例,结果应该是项目1043
因为它在所有仓库中都可用,与其他仓库不同。
我没有得到解决方案,任何人都可以帮助我吗?
你也可以使用NOT EXISTS
使用这个“双阴性”查询:
SELECT DISTINCT s.ItemID
FROM StockTable s
WHERE NOT EXISTS
(
SELECT 1 FROM Warehouse w
WHERE NOT EXISTS(SELECT 1 FROM StockTable s2
WHERE w.WarehouseID = s2.WarehouseID
AND s.ItemID = s2.ItemID)
)
这种方法看起来更冗长,但它有一些好处:
GROUP BY
select itemid
from stock
group by itemid
having count(distinct warehouseid) = (select count(*) from warehouse);
SQLFiddle: http ://sqlfiddle.com/#!15 / e4273 / 1
如果stock表还可能包含amount = 0的项,则需要添加where子句:
select itemid
from stock
where itemamount > 0
group by itemid
having count(distinct warehouseid) = (select count(*) from warehouse);
NOT EXISTS
结合EXCEPT
:
select distinct ItemID
from stock s1
where not exists (select warehouseid from warehouse
except
select warehouseid from stock s2 where s2.ItemID = s1.ItemID);
您甚至可以用select *
替换select distinct ItemID
来获取所有这些项目。
我用这个查询:
SELECT
ItemID
FROM
stock
GROUP BY
ItemID
HAVING
SUM(DISTINCT warehouseid) = (SELECT SUM(WarehouseID) from warehouse)
这比使用COUNT
更可靠,因为在极少数情况下不使用外键它应该返回一些无效结果。
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