我有一张桌子

create table us
(
 a number
);

现在我有如下数据:

a
1
2
3
4
null
null
null
8
9

现在我需要一个查询来计算列a中的空值和非空值


当前回答

Try

SELECT 
   SUM(ISNULL(a)) AS all_null,
   SUM(!ISNULL(a)) AS all_not_null
FROM us;

简单!

其他回答

下面是一个在Oracle上运行的快速而简单的版本:

select sum(case a when null then 1 else 0) "Null values",
       sum(case a when null then 0 else 1) "Non-null values"
from us

如果是mysql,你可以尝试这样做。

select 
   (select count(*) from TABLENAME WHERE a = 'null') as total_null, 
   (select count(*) from TABLENAME WHERE a != 'null') as total_not_null
FROM TABLENAME

试试这个. .

SELECT CASE 
         WHEN a IS NULL THEN 'Null' 
         ELSE 'Not Null' 
       END a, 
       Count(1) 
FROM   us 
GROUP  BY CASE 
            WHEN a IS NULL THEN 'Null' 
            ELSE 'Not Null' 
          END 

对于非空值

select count(a)
from us

null值

select count(*)
from us

minus 

select count(a)
from us

因此

SELECT COUNT(A) NOT_NULLS
FROM US

UNION

SELECT COUNT(*) - COUNT(A) NULLS
FROM US

应该做这项工作

更好的是列标题是正确的。

SELECT COUNT(A) NOT_NULL, COUNT(*) - COUNT(A) NULLS
FROM US

在我的系统上进行的一些测试中,需要进行全表扫描。

这里有两种解决方案:

Select count(columnname) as countofNotNulls, count(isnull(columnname,1))-count(columnname) AS Countofnulls from table name

OR

Select count(columnname) as countofNotNulls, count(*)-count(columnname) AS Countofnulls from table name