Mysql查詢需要減去無法引用的字段

Question

我們的db將客戶訂單存儲在兩個表中：customerorders和customerorderlines。 在其他字段中，有一個customerorders.type字段，它確定（= 1或= 2） 該customerorder是發票還是信用證。

目前我們有一個報告，列出售出的單位數量，利潤等，但其目前的查詢，只顯示售出超過期限，即，它不扣除的積分數總檯，如果有的話。這裏是它的SQL和它產生的結果的一個例子：

（道歉隨後的大量查詢:)）

SELECT l.name AS locationname 
, sr.name AS salesrepname 
, ct.name AS customertypename 
, c.name AS customername 
, c.id AS customer_id 
, c.code 
, s.name AS suppliername 
, p.description AS productname 
, p.id AS product_id 
, p.unitofmeasure 
, SUM(col.vatableprice) AS totalsales 
, SUM(col.vatprice) AS vat 
, SUM(col.quantity) AS totalitems 
, SUM(col.quantity * col.costprice) AS totalsalecost 
, SUM(col.vatableprice) - SUM(col.quantity * col.costprice) AS totalprofit 
,(
    SELECT SUM(col2.vatableprice) AS totalsales 
    FROM customerorders AS co2 
    LEFT JOIN customerorderlines AS col2 ON col2.customerorder_id = co2.id 
    LEFT JOIN customers AS c2 ON c2.id = co2.customer_id 
    LEFT JOIN locations AS l2 ON l2.id = c2.location_id 
    LEFT JOIN customertypes AS ct2 ON ct2.id = c2.customertype_id 
    LEFT JOIN salesreps AS sr2 ON sr2.id = c2.salesrep_id 
    LEFT JOIN products AS p2 ON p2.id = col2.product_id 
    LEFT JOIN suppliers AS s2 ON s2.id = p2.supplier_id 
    WHERE c.salesrep_id = c2.salesrep_id 
    AND co2.type = 2 AND p2.supplier_id = 179 
    AND co2.orderdate >= '2010-01-01 00:00:00' 
    AND co2.orderdate <= '2010-02-01 23:59:59' 
) AS credits 
,(
    SELECT SUM(col2.vatprice) AS totalvat FROM customerorders AS co2 
    LEFT JOIN customerorderlines AS col2 ON col2.customerorder_id = co2.id 
    LEFT JOIN customers AS c2 ON c2.id = co2.customer_id 
    LEFT JOIN locations AS l2 ON l2.id = c2.location_id 
    LEFT JOIN customertypes AS ct2 ON ct2.id = c2.customertype_id 
    LEFT JOIN salesreps AS sr2 ON sr2.id = c2.salesrep_id 
    LEFT JOIN products AS p2 ON p2.id = col2.product_id 
    LEFT JOIN suppliers AS s2 ON s2.id = p2.supplier_id 
    WHERE c.salesrep_id = c2.salesrep_id 
    AND co2.type = 2 
    AND p2.supplier_id = 179 
    AND co2.orderdate >= '2010-01-01 00:00:00' 
    AND co2.orderdate <= '2010-02-01 23:59:59' 
) AS creditsvat 

FROM customerorders AS co 
LEFT JOIN customerorderlines AS col ON col.customerorder_id = co.id 
LEFT JOIN customers AS c ON c.id = co.customer_id 
LEFT JOIN locations AS l ON l.id = c.location_id 
LEFT JOIN customertypes AS ct ON ct.id = c.customertype_id 
LEFT JOIN salesreps AS sr ON sr.id = c.salesrep_id 
LEFT JOIN products AS p ON p.id = col.product_id 
LEFT JOIN suppliers AS s ON s.id = p.supplier_id 
WHERE co.status_v = 5 
AND co.type = 1 
AND p.supplier_id = 179 
AND co.orderdate >= '2010-01-01 00:00:00' AND co.orderdate <= '2010-02-01 23:59:59' 
GROUP BY c.salesrep_id 

其中，在這種情況下（分組等是由應用程序代碼所確定的），生成一個「每個銷售代表」報告：

Rep | TotalItems | SalesValue| CostOfSales | Profit | VAT  | Credits | Credits(VAT) 
Rep1| 937  | £5796.49 | £3606.49 | £2190.00 | £1013.73 | £220.12 | £38.57 
Rep2| 1905  | £11695.09 | £7314.95 | £4380.14 | £2045.32 | £268.85 | £47.00 
Rep3| 1074  | £6346.61 | £3950.53 | £2396.08 | £1109.76 | £54.89 | £9.57 
Rep4| 2687  | £16129.42 | £10171.65 | £5957.77 | £2820.46 | £839.15 | £146.78 

那麼，問題在於，TOTALITEMS是所銷售項目的絕對數量（類型= 1的所有customerorders）。信用字段顯示類型= 2期間的項目的總成本，即返回。 TotalItems應該有從其中扣除的信用數量，所以一眼就可以看到實際上已售出的東西，當然所有其他領域也需要他們的信用卡對方也相互扣除，以便它們反映出售物品的正確金額。

起初，我認爲這將是對現有查詢的簡單修改，但後來發現我無法在選擇中引用子查詢別名，因此我使用JOIN（SELECT ....）重寫了整個查詢。加入（選擇.....）作爲學分，所以我可以從查詢頂部的SELECT引用sales.qty和credits.qty，但除非你做了小的查詢，否則那根本沒有規模。

這是多遠我得到：

（的確，我查詢了這裏不同的東西......這將是基本的查詢的最簡單形式：單品銷售/學分）

SELECT sr.name AS salesrepsname 
,l.name AS locationname 
,sup.name AS suppliername 
,p.description AS productname 
,sales.qty AS sold 
,credits.qty AS credits 
,sales.qty - credits.qty AS actualsold 
FROM 
customerorders co 
LEFT JOIN customerorderlines col ON col.customerorder_id = co.id 
LEFT JOIN customers c ON c.id = co.customer_id 
LEFT JOIN products p ON p.id = col.product_id 
LEFT JOIN salesreps sr ON sr.id = c.salesrep_id 
LEFT JOIN locations l ON l.id = c.location_id 
LEFT JOIN suppliers sup ON sup.id = p.supplier_id 
JOIN (SELECT SUM(col.quantity) AS qty, 
SUM(col.vatableprice) AS total FROM customerorderlines col 
LEFT JOIN customerorders co ON co.id = col.customerorder_id 
WHERE col.product_id = 27642 AND co.type = 1) 
AS sales 
JOIN (SELECT SUM(col2.quantity) AS qty FROM customerorderlines col2 
LEFT JOIN customerorders co2 ON co2.id = col2.customerorder_id 
WHERE col2.product_id = 27642 AND co2.type = 2) AS credits 
WHERE col.product_id = 27642 
GROUP BY c.salesrep_id 

所以我不得不承認我有點卡住了，並不是很熟悉mysql。

任何建議都非常歡迎，請隨時點我朝着先進的subquerying任何文學和加入，我應該去閱讀。

乾杯！

Answer 1

我認爲你可能正在尋找的技巧是沿着這些線。在你想修正的任何給定的查詢/子查詢中，使用一些這樣的SQL，選擇所有行，不管它是發票還是信用註釋，並根據訂單/貨幣的方式總結一個正值或負值的值去：

SELECT 
    SUM(CASE WHEN co.type = 1 THEN col.quantity ELSE -col.quantity END) 
FROM 
    ... 

得到它嗎？您可以將所有訂單項都拿回來，但是當您完成這筆交易時，您將累計正信用和負借記金額，以便在一次操作中獲得實際總金額。