嘗試組合行

我認爲我的DISTINCT語句有助於按order.customer_num進行分組，但似乎並非如此。我相信這與我的SELECT語句中的表達式有關。真的很新的SQL。嘗試組合行

SELECT DISTINCT orders.customer_num AS "Customer Number", 
     COUNT(orders.order_num) AS "Number of Orders", 
     SUM(items.quantity) AS "Total Quantity", stock.unit_price AS "Unit Price", 
     items.quantity * stock.unit_price AS "Total Price" 
FROM orders, 
    items, 
    stock 
WHERE orders.order_num = items.order_num 
    AND items.stock_num = stock.stock_num 
GROUP BY orders.customer_num, items.quantity, stock.unit_price 
ORDER BY orders.customer_num;

附上一張照片，顯示我所得到的。 My Result

來源

2017-09-14 Mark Anguiano

你可以請附上表格說明。你確定你想把他們與客戶編號分開嗎？如果是這種情況，你得到的結果是正確的，因爲結果數據顯示，對於每個客戶，許多項目已被購買（如果我的假設是正確的，那是一個項目爲每個單位價格）。 – brenners1302

添加一些示例表格數據和預期結果 - 作爲格式化文本（而不是圖像）。另外，GROUP BY時很少需要SELECT DISTINCT。 – jarlh

今天提示：切換到現代，明確的'JOIN'語法。易於編寫（沒有錯誤），更易於閱讀和維護，並且在需要時更容易轉換爲外部聯接。 – jarlh

您的stock.unit_price似乎是唯一的。從邏輯上說，它選擇unit_price每item。要麼您需要丟棄stock表和相關的加入條件或總結

來源

2017-09-14 05:26:04

您是否想要group由客戶計算並計算所有列的總數？如果我對你不需要group byitems.quantity, stock.unit_price列和distinct，試試這個

SELECT orders.customer_num AS "Customer Number", 
     COUNT(orders.order_num) AS "Number of Orders", -- or SUM() depends on your logic 
     SUM(items.quantity) AS "Total Quantity", 
     SUM(stock.unit_price) AS "Unit Price", 
     SUM(items.quantity * stock.unit_price) AS "Total Price" 
FROM orders, items, stock 
WHERE orders.order_num = items.order_num 
    AND items.stock_num = stock.stock_num 
GROUP BY orders.customer_num 
ORDER BY orders.customer_num;

來源

2017-09-14 06:30:42 Vecchiasignora

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