SQL Count空字段

Question

我不确定这是否可行,或者是否可行,如何做到 -

我在数据库中有以下数据 -

id     |    improve |   timeframe |  criteria |  impact
-------+------------+-------------+-----------+--------- 
1      |            |    Test     |   Test    |    Test
2      |    Test    |             |   Test    |   
3      |            |    Test     |           |    
-------+------------+-------------+-----------+--------- 

忽略id列,如何使用SQL查询确定其余12个中非空的字段数？

我已经开始 -

SELECT improve, timeframe, impact, criteria 
FROM data 
WHERE improve IS NOT NULL 
  AND timeframe IS NOT NULL 
  AND impact IS NOT NULL 
  AND criteria IS NOT NULL;

这只返回行数,即.3.

有任何想法吗？

谢谢.

Answer 1

SELECT count(improve) + count(timeframe) + count(impact) + count(criteria) FROM data 

Answer 2

像这样的事情可能会让你朝着正确的方向前进

SELECT 
SUM(CASE WHEN improve IS NULL THEN 0 ELSE 1 END +
CASE WHEN timeframe IS NULL THEN  0 ELSE 1 END +
CASE WHEN criteria IS NULL THEN  0 ELSE 1 END +
CASE WHEN impact IS NULL THEN  0 ELSE 1 END)
from
data