多输出一个SQL查询

Question

我想写一个SQL查询，将输出多个变量，具体取决于数据库中存在特定数量的次数。这些信息将在图表中使用。

的DB设置如下：

ID | quantity | etc.. 
--------------------- 
1 | 2  | 
2 | 6  | 
3 | 1  | 
4 | 2  | 
. 
. 
. 

这里是我进行的查询：

SELECT 
    COUNT(CASE WHEN quantity = 1) AS quantity1, 
    COUNT(CASE WHEN quantity = 2) AS quantity2 
FROM orders 

但我希望它输出这样的：

quantity1 | quantity2 
--------------------- 
    1  | 2  | 

相反，我我得到这些错误信息：

在此先感谢！

编辑：如果你想在我的数据库测试你的代码，链接低于...

-Link被切除，

Answer 1

这里是另一种方法，也许它可以帮助：

SELECT SUM(CASE WHEN quantity = 1 THEN 1 ELSE 0 END) AS quantity_1, 
     SUM(CASE WHEN quantity = 2 THEN 1 ELSE 0 END) AS quantity_2, 
     SUM(CASE WHEN quantity = 3 THEN 1 ELSE 0 END) AS quantity_3, 
     SUM(CASE WHEN quantity = 4 THEN 1 ELSE 0 END) AS quantity_4, 
     SUM(CASE WHEN quantity = 5 THEN 1 ELSE 0 END) AS quantity_5, 
     SUM(CASE WHEN quantity = 6 THEN 1 ELSE 0 END) AS quantity_6, 
     SUM(CASE WHEN quantity > 6 THEN 1 ELSE 0 END) AS quantity_more_than_6 
    FROM orders 

这里是MS Access中的一个特殊查询：

SELECT SUM(SWITCH(quantity = 1, 1)) AS quantity_1, 
     SUM(SWITCH(quantity = 2, 1)) AS quantity_2, 
     SUM(SWITCH(quantity = 3, 1)) AS quantity_3, 
     SUM(SWITCH(quantity = 4, 1)) AS quantity_4, 
     SUM(SWITCH(quantity = 5, 1)) AS quantity_5, 
     SUM(SWITCH(quantity = 6, 1)) AS quantity_6, 
     SUM(SWITCH(quantity > 6, 1)) AS quantity_more_than_6 
    FROM orders 

Answer 2

使用GROUP BY子句，是这样的：

SELECT quantity, COUNT(*) AS num 
FROM Orders 
GROUP BY quantity 
HAVING COUNT(*) > 6; 

编辑：您可以添加HAVING子句