SQL 使用计算字段加入 table

Question

我想在此查询中添加另一列以显示需要处理的延期交货。

目前 table 显示所有具有未清商品的订单以及包含的每个库存参考的库存量。

我想为建议的发票金额添加一个字段。即如果订单数量为5，发票数量为2，库存数量为2，则建议发货2。

如果库存量为100则建议发货3。

我目前的尝试如下，但我不知道如何做最后一点。

我知道我需要做 (qtyOrdered-qtyinvoiced) 但真的碰壁了。

SELECT 
    c.cus_name,
    ol.orderLines_stockRef,
    ol.orderLines_qtyOrdered,
    ol.orderlines_qtyInvoiced,
    pr.products_instock
FROM
    cus c
        JOIN
    orderheader oh ON oh.orderHeader_customer = c.cus_id
        JOIN
    orderlines ol ON ol.orderLines_orderId = oh.orderHeader_id
        JOIN
    products pr ON ol.orderlines_stockref = pr.products_reference
WHERE
    ol.orderLines_qtyOrdered <> ol.orderlines_qtyInvoiced

当前输出：

Answer 1

试试这个：

SELECT 
    c.cus_name,
    ol.orderLines_stockRef,
    ol.orderLines_qtyOrdered,
    ol.orderlines_qtyInvoiced,
    pr.products_instock,
    (CASE WHEN ol.orderLines_qtyOrdered - ol.orderlines_qtyInvoiced > pr.products_instock
          THEN pr.products_instock
          ELSE ol.orderLines_qtyOrdered - ol.orderlines_qtyInvoiced) AS qtyToSend,
FROM
    cus c
        JOIN
    orderheader oh ON oh.orderHeader_customer = c.cus_id
        JOIN
    orderlines ol ON ol.orderLines_orderId = oh.orderHeader_id
        JOIN
    products pr ON ol.orderlines_stockref = pr.products_reference
WHERE
    ol.orderLines_qtyOrdered <> ol.orderlines_qtyInvoiced

SQL 使用计算字段加入 table

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