SQL 查詢中列名不明確的錯誤

Question

我有兩個查詢。 第一個是：

SELECT hardware, SUM(Quantity) FROM request_1v2 where date between "2016-03-12" AND "2016-03-14" group by hardware

第一個查詢的輸出是

第二個查詢是：

SELECT hardware, SUM(Quantity) FROM request_1v2 where date between "2016-03-12" AND "2016-03-12" group by hardware

第二個查詢的輸出是：

實際上我正在繪制一個圖所以我需要將這兩個查詢合並為一個。 我得到的解決方案是：

SELECT t1.hardware, SUM(t1.Quantity), SUM(t2.Quantity) 
FROM request_1v2 AS t1,request_1v2 AS t2 
WHERE t1.date between "2016-03-12" and "2016-03-14" AND t2.date between "2016-03-12" and "2016-03-12" 
GROUP BY t1.hardware

解決方案查詢的輸出：

這是錯誤的！

我需要的實際輸出將是：-

我不知道該怎么做。 誰能幫我。？ 有人建議我將您的查詢寫為：-

SELECT hardware, SUM(t1.Quantity), SUM(t2.Quantity) 
FROM request_1v2 AS t1,request_1v2 AS t2 
WHERE t1.date between "2016-03-12" and "2016-03-14" AND t2.date between "2016-03-12" and "2016-03-12" 
GROUP BY hardware

但它給出了錯誤“不明確的列名：硬件”

請幫助我並編寫查詢作為您的答案謝謝。

如果你需要表結構，這里是：

Answer 1

只需使用 CASE，您的日期重疊，您可能想要更改它們。由於您沒有 JOIN 條件，因此您的第三個查詢創建了笛卡爾 JOIN。

SELECT hardware, 
SUM(CASE WHEN date between "2016-03-12" AND "2016-03-14" THEN Quantity ELSE 0 END),
SUM(CASE WHEN date between "2016-03-12" AND "2016-03-12" THEN Quantity ELSE 0 END)
 FROM request_1v2 
group by hardware