Question

我有这张桌子

表名：com_inv

item_name   amount  date_added
item 1      1       06/06/2015
item 2      2       07/06/2015
item 3      3       08/06/2015
item 1      10      09/06/2015
item 2      20      10/06/2015
item 3      30      11/06/2015

表名：sls_ordrs

item_name   amount  order_status    date_received
item 1      1       received        06/06/2015
item 2      1       delivered   
item 3      2       received        08/06/2015
item 1      5       received        09/06/2015
item 2      5       delivered   
item 3      2       received        11/06/2015

我想要达到的目标是，每个项目减去sls_ordrs中已经收到的金额总和＆＃34;来自com_inv中金额的总和。结果表应如下所示：

Item Name   Stocked Dispensed   Remaining
item 1      11      6           5
item 2      22      0           22
item 3      33      4           29

如果我使用SQL Server，我只会使用CTE但是使用MySql我需要你的帮助。这是我到目前为止提出的代码......

SELECT
    a.item_name,
    b.stocked AS 'Stocked',
    sum(a.amount) AS 'Dispensed',
    IFNULL(b.stocked, 0) - IFNULL(a.amount, 0) AS 'Remaining'
FROM
    sls_ordrs a
LEFT JOIN (
    SELECT
        item_name AS 'item_name',
        SUM(amount) AS 'stocked'
    FROM
        com_inv
    GROUP BY
        item_name
) b ON a.item_name = b.item_name
WHERE
    a.order_status = 'received'
GROUP BY
    item_name

这里的库存列给了我一个空值。

Answer 1

使用此查询。希望它应该工作正常。

SQL FIDDLE DEMO

SELECT
    I.item_name,
    I.Stocked,
    S.Dispensed,
    COALESCE (I.Stocked, 0) - COALESCE (S.Dispensed, 0) AS Remaining
FROM
    (
        SELECT
            item_name AS 'item_name',
            SUM(amount) AS 'Stocked'
        FROM
            com_inv
        GROUP BY
            item_name
    ) I
LEFT JOIN (
    SELECT
        item_name,
        order_status,
        SUM(amount) AS Dispensed
    FROM
        sls_ordrs
    WHERE
        order_status = 'received'
    GROUP BY
        item_name
) S ON I.item_name = S.item_name;

将传递的值相加并从接收到的值中减去它，并使用相同的名称mysql

1 个答案: