非空的所有列的计数

Question

用于提取非空的所有列的计数的查询;

id | Col1 | Col2 | Col3 | Col4 | 
-------------------------------- 
1 | abc | --- | xyz | pqr | 
-------------------------------- 
2 | def | ghi | --- | pqr | 
-------------------------------- 
3 | --- | --- | hgy | --- | 
-------------------------------- 
4 | --- | jko |  | uyi | 
-------------------------------- 

SELECT COUNT(*) FROM table 1 WHERE Col1!='---' 

SELECT COUNT(*) FROM table 1 WHERE Col2!='---' 

SELECT COUNT(*) FROM table 1 WHERE Col3!='---' 

在一个单一的查询

如何获得的结果作为

----------------------- 
Cnt1| Cnt2 |Cnt3| Cnt4| 
----------------------- 
2 | 2 | 2 | 3 | 
----------------------- 

Answer 1

有趣的是：

select count(col1) cnt1, count(col2) cnt2, count(col3) cnt3, count(col4) cnt4 
from table1 

Answer 2

试试这个：

with data as (
    select * 
    from (values 
     (null, null, null, null), 
     ( 1, null, null, null), 
     ( 2, 4, null, null), 
     ( 0, 5, 6, null) 
) data(col1,col2,col3,col4) 
) 
select 
    sum(case when col1 is null then 0 else 1 end), 
    sum(case when col2 is null then 0 else 1 end), 
    sum(case when col3 is null then 0 else 1 end), 
    sum(case when col4 is null then 0 else 1 end) 
from data 

这很好地产生：

----------- ----------- ----------- ----------- 
      3   2   1   0 

Answer 3

看起来你有 '---' 值，而不是空值。在这种情况下：

select count(nullif(col1,'---')) as cnt1, count(nullif(col2,'---')) as cnt2, count(nullif(col1,'---')) as cnt3, count(nullif(col1,'---')) as cnt4 from table1;