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

select count(isnull(NullableColumn,-1))

其他回答

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

这在T-SQL中有效。如果你只是计算一些东西的数量,你想包括空值,使用COALESCE而不是case。

IF OBJECT_ID('tempdb..#us') IS NOT NULL
    DROP TABLE #us

CREATE TABLE #us
    (
    a INT NULL
    );

INSERT INTO #us VALUES (1),(2),(3),(4),(NULL),(NULL),(NULL),(8),(9)

SELECT * FROM #us

SELECT CASE WHEN a IS NULL THEN 'NULL' ELSE 'NON-NULL' END AS 'NULL?',
        COUNT(CASE WHEN a IS NULL THEN 'NULL' ELSE 'NON-NULL' END) AS 'Count'
    FROM #us
    GROUP BY CASE WHEN a IS NULL THEN 'NULL' ELSE 'NON-NULL' END

SELECT COALESCE(CAST(a AS NVARCHAR),'NULL') AS a,
        COUNT(COALESCE(CAST(a AS NVARCHAR),'NULL')) AS 'Count'
    FROM #us
    GROUP BY COALESCE(CAST(a AS NVARCHAR),'NULL')

用于计数非空值

select count(*) from us where a is not null;

用于计算空值

 select count(*) from us where a is null;

Try

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

简单!

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。