选择计数“空”和“非空”

Question

下选择工作时CLOSE_DATE场IS NOT NULL：

SELECT 
    YEAR (CLOSE_DATE) AS TheYear, 
    MONTH (CLOSE_DATE) AS TheMonth, 
    COUNT (*) AS cnt 
FROM 
    Table1 
WHERE 
    Table1.DEPT = 'SUPPORT' 
GROUP BY 
    YEAR (CLOSE_DATE), 
    MONTH (CLOSE_DATE) 
ORDER BY 
    TheYear DESC, 
    TheMonth DESC 

输出是：

+-------------+------+ 
| Year | Month | cnt | 
+-------------+------+ 
| 2014 |  4 | 10 | 
| 2014 |  3 | 9 | 
| 2014 |  2 | 15 | 
| 2014 |  1 | 12 | 
| 2013 | 12 | 10 | 
| 2013 | 11 | 50 | 
+--------------+-----+ 

如果CLOSE_DATE有，例如，7行NULL，结果将为：

+-------------+------+ 
| Year | Month | cnt | 
+-------------+------+ 
| NULL | NULL | 7 | 
| 2014 |  4 | 10 | 
| 2014 |  3 | 9 | 
| 2014 |  2 | 15 | 
| 2014 |  1 | 12 | 
| 2013 | 12 | 10 | 
| 2013 | 11 | 50 | 
+--------------+-----+ 

NULL表明它应该算的实际年份和月份，所以预期的结果应该是：

+-------------+------+ 
| Year | Month | cnt | 
+-------------+------+ 
| 2014 |  4 | 17 | 
| 2014 |  3 | 9 | 
| 2014 |  2 | 15 | 
| 2014 |  1 | 12 | 
| 2013 | 12 | 10 | 
| 2013 | 11 | 50 | 
+--------------+-----+ 

UPDATE

上面的例子只是一个更大的选择的一部分。我实际上计算了打开和关闭的情况。

如果票证没有close_date，则表示它已打开。所以，计数接近它应该算作公开。

的选择是一样的，用开柱：

SELECT 
    YEAR (OPEN_DATE) AS TheYear, 
    MONTH (OPEN_DATE) AS TheMonth, 
    COUNT (*) AS cnt 
FROM 
    Table1 
WHERE 
    Table1.DEPT = 'SUPPORT' 
GROUP BY 
    YEAR (OPEN_DATE), 
    MONTH (OPEN_DATE) 
ORDER BY 
    TheYear DESC, 
    TheMonth DESC 

所以行YEAR (OPEN_DATE) AS TheYear,和MONTH (OPEN_DATE) AS TheMonth,带来的年份和月份从open_date列，但如果close_date列is null它应该算在该行太。

这样，所有在close_date中具有空值的行将被视为open_date。

Answer 1

您可以使用Isnull()函数，只要发生值null，此函数就允许使用另一个预定义值。

SELECT 
    YEAR (Isnull(CLOSE_DATE,getdate())) AS TheYear, 
    MONTH (Isnull(CLOSE_DATE,getdate())) AS TheMonth, 
    COUNT (*) AS cnt 
FROM 
    Table1 
WHERE 
    Table1.DEPT = 'SUPPORT' 
GROUP BY 
    YEAR (Isnull(CLOSE_DATE,getdate())), 
    MONTH (Isnull(CLOSE_DATE,getdate())) 
ORDER BY 
    TheYear DESC, 
    TheMonth DESC