sqlite返回子查詢多列

Question

我有一個sqlite子查詢，下面的查詢是計算小時和labour_rate。我現在唯一的問題是我可以從我的子查詢中獲取兩列以輸出主查詢。我試圖根據一些網站的教程來佈置查詢，但需要的幫助，有點讓我過了終點線，我不斷收到一個語法錯誤

SELECT c.customerID, c.customer, sum(ifnull(il.line_price, 0))/10000 AS net, 
    FROM customer AS c 
    LEFT JOIN invoice AS i 
    ON c.customerID = i.customerID 
    LEFT JOIN invoice_line AS il 
    ON i.invoiceID = il.invoiceID 
    (SELECT sum((ifnull(tl.mon,0) + ifnull(tl.tues,0) + ifnull(tl.wed,0) + ifnull(tl.thurs,0) + ifnull(tl.fri,0) + ifnull(tl.sat,0) + ifnull(tl.sun,0)) * s.cost_rate)/10000 AS labour_rate, 
    sum((ifnull(tl.mon,0) + ifnull(tl.tues,0) + ifnull(tl.wed,0) + ifnull(tl.thurs,0) + ifnull(tl.fri,0) + ifnull(tl.sat,0) + ifnull(tl.sun,0)))/10000 AS 
    FROM timesheet_line AS tl 
    LEFT JOIN timesheet AS t 
    ON tl.timesheetID = t.timesheetID 
    LEFT JOIN staff AS s 
    ON t.staffID = s.staffID 
    WHERE (c.customerID = tl.customerID) AND (t.date BETWEEN '2014-03-01' AND '2015-12-01') 
    GROUP BY tl.customerID) AS time1 
    WHERE (i.date BETWEEN '2014-03-01' AND '2015-12-01') AND (time1.customerID = tl.customerID) 
    GROUP BY c.customerID 
    ORDER BY c.customer ASC 

Answer 1

中有幾個語法錯誤這裏。第一個（也可能是最重要的）是你必須將子查詢JOIN分配給結果集的其餘部分。所以經過

LEFT JOIN invoice_line AS il 
    ON i.invoiceID = il.invoiceID 

你將需要添加另一個JOIN語句：

LEFT JOIN 
    (SELECT 
     SUM(...) AS labour_rate, 
     SUM(...) AS hours, 
     tl.customerID 
    FROM 
    ...) AS time1 
ON <your join condition> 

你會在你的子查詢中選擇一些排序字段，你可以加入回發票上即tl.customerID 。 另外，在你的子查詢中，你不能引用它之外的字段，所以當你的子查詢中有WHERE (c.customerID = tl.customerID)時，它會失敗，因爲你試圖引用c.<fieldname>。它需要移至JOIN子句的ON部分。一旦你的JOIN正常工作，那麼你可以改變你的最外層SELECT喜歡的東西

SELECT c.customerID, c.customer, sum(ifnull(il.line_price,0))/10000 AS net, time1.labour_rate, time1.hours 

這裏是我會怎麼做一個例子：

SELECT c.customerID, c.customer, sum(ifnull(il.line_price, 0))/10000 AS net, time1.labour_rate, time1.[hours] 
FROM customer AS c 
    LEFT JOIN invoice AS i 
    ON c.customerID = i.customerID 
    LEFT JOIN invoice_line AS il 
    ON i.invoiceID = il.invoiceID 
    LEFT JOIN 
     (SELECT 
      sum((ifnull(tl.mon,0) + ifnull(tl.tues,0) + ifnull(tl.wed,0) + ifnull(tl.thurs,0) + ifnull(tl.fri,0) + ifnull(tl.sat,0) + ifnull(tl.sun,0)) * s.cost_rate)/10000 AS labour_rate, 
      sum((ifnull(tl.mon,0) + ifnull(tl.tues,0) + ifnull(tl.wed,0) + ifnull(tl.thurs,0) + ifnull(tl.fri,0) + ifnull(tl.sat,0) + ifnull(tl.sun,0)))/10000 AS [hours], 
      tl.customerID 
     FROM timesheet_line AS tl 
      LEFT JOIN timesheet AS t 
      ON tl.timesheetID = t.timesheetID 
      LEFT JOIN staff AS s 
      ON t.staffID = s.staffID 
     WHERE (t.date BETWEEN '2014-03-01' AND '2015-12-01') 
     GROUP BY tl.customerID) AS time1 
    ON c.customerID = time1.customerID 
WHERE (i.date BETWEEN '2014-03-01' AND '2015-12-01') 
GROUP BY c.customerID 
ORDER BY c.customer ASC