总和项目&；具有多个表的数量&；如果MySQL

我想显示所有带有数量的项目。但数量在不同的表中

示例输出：

Item    Quantity
Item1   34
Item2   10
Item3   0
........

我有一个代码，可以计数数量，但只能在单个项目中。

SELECT SUM(ROUND(Quantity)) FROM(
SELECT
COALESCE(SUM(od.Quantity),0) as 'Quantity'
FROM sts as T1
LEFT JOIN orderset_details as od ON T1.OrdersetId = od.OrdersetId
WHERE od.ItemId = '4786' 
UNION ALL
SELECT 
COALESCE(SUM(od.Quantity),0) as 'Quantity'
FROM drs as T2
LEFT JOIN orderset_details as od ON T2.OrdersetId = od.OrdersetId
WHERE od.ItemId = '4786' 
UNION ALL  
SELECT 
COALESCE(SUM(IF(r.AddsToStock = '1', od.Quantity, 0 - od.Quantity)),0) as 'Quantity'
FROM stockadjustment as T3
LEFT JOIN reason as r ON r.ReasonId = T3.ReasonId
LEFT JOIN orderset_details as od ON T3.OrdersetId = od.OrdersetId 
WHERE od.ItemId = '4786'
UNION ALL
SELECT 
COALESCE(SUM(IF(T4.OrdersetId = od.OrdersetId, 0 - od.Quantity, -1 * od.Quantity)),0) as 'Quantity'
FROM issueslip as T4
LEFT JOIN orderset_details as od ON T4.OrdersetId = od.OrdersetId 
WHERE od.ItemId = '4786'
UNION ALL
SELECT 
COALESCE(SUM(IF(T4.OrdersetId = od.OrdersetId, 0 - od.Quantity, -1 * od.Quantity)),0) as 'Quantity'
FROM invoice as T4
LEFT JOIN orderset_details as od ON T4.OrdersetId = od.OrdersetId
WHERE od.ItemId = '4786') as t

如何使用此代码实现项目？

表名

项

且id为

ItemId

创建此存储函数：

DELIMITER //

CREATE FUNCTION getItemQty(
    _itemID INT(10)
)
RETURNS INT
BEGIN

RETURN (SELECT 
        SUM(ROUND(Quantity)) 
    FROM (
        SELECT
            COALESCE(SUM(od.Quantity),0) as Quantity
        FROM sts as T1
        LEFT JOIN orderset_details as od 
            ON T1.OrdersetId = od.OrdersetId
        WHERE od.ItemId = _itemID
        UNION ALL
        SELECT 
            COALESCE(SUM(od.Quantity),0) as Quantity
        FROM drs as T2
        LEFT JOIN orderset_details as od 
            ON T2.OrdersetId = od.OrdersetId
        WHERE od.ItemId = _itemID
        UNION ALL  
        SELECT 
            COALESCE(
                SUM(
                    IF(r.AddsToStock = '1', od.Quantity, 0 - od.Quantity)
                ),0
            ) as Quantity
        FROM stockadjustment as T3
        LEFT JOIN reason as r 
            ON r.ReasonId = T3.ReasonId
        LEFT JOIN orderset_details as od 
            ON T3.OrdersetId = od.OrdersetId 
        WHERE od.ItemId = _itemID
        UNION ALL
        SELECT 
            COALESCE(
                SUM(
                    IF(T4.OrdersetId = od.OrdersetId, 0 - od.Quantity, -1 * od.Quantity)
                ),0
            ) as Quantity
        FROM issueslip as T4
        LEFT JOIN orderset_details as od 
            ON T4.OrdersetId = od.OrdersetId 
        WHERE od.ItemId = _itemID
        UNION ALL
        SELECT 
            COALESCE(
                SUM(
                    IF(T4.OrdersetId = od.OrdersetId, 0 - od.Quantity, -1 * od.Quantity)
                ),0
            ) as Quantity
        FROM invoice as T4
        LEFT JOIN orderset_details as od 
            ON T4.OrdersetId = od.OrdersetId
        WHERE od.ItemId = _itemID
    ) as t);
END//

使用该查询获取数据

SELECT 
    ItemId,
    getItemQty(ItemId) AS quantity
FROM items

---

我稍后会试试，因为我需要一些睡眠，但我想这就是我想要的：）我稍后会测试。感谢您回答（y）

#1054-where子句中的未知列“i.ItemId”

我明白了，这是因为我们有两级子查询，无法访问外部查询的数据。尝试第二个查询。如果它不起作用，我仍然可以尝试一些东西。我不知道如何使用该查询实现

items

表。我不知道。我真的需要你的帮助。你是说

项
表还不存在吗？抱歉，让我概括一下，您的项分布在查询中使用的所有表中，您希望将数据重新组合到一个表中。这是你想要的吗？<代码>左联接X，其中X <代码>与<代码>内部连接X <代码>相同。如果你愿意，考虑下面的简单的两步过程：1。如果您还没有这样做，请提供适当的CREATE和INSERT语句（和/或SQLFIDLE），以便我们可以更轻松地复制问题。2.如果您还没有这样做，请提供一个与步骤1中提供的信息相对应的所需结果集。@很抱歉，我是MySQL新手，尽管我使用MySQL已经多年了。这是我第一次遇到太多的加入。