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
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
正如我理解你的查询,你只需要运行这个脚本并获得Total Null,Total NotNull行,
select count(*) - count(a) as 'Null', count(a) as 'Not Null' from us;
其他回答
正如我理解你的查询,你只需要运行这个脚本并获得Total Null,Total NotNull行,
select count(*) - count(a) as 'Null', count(a) as 'Not Null' from us;
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。
在我的例子中,我想要多列之间的“空分布”:
SELECT
(CASE WHEN a IS NULL THEN 'NULL' ELSE 'NOT-NULL' END) AS a_null,
(CASE WHEN b IS NULL THEN 'NULL' ELSE 'NOT-NULL' END) AS b_null,
(CASE WHEN c IS NULL THEN 'NULL' ELSE 'NOT-NULL' END) AS c_null,
...
count(*)
FROM us
GROUP BY 1, 2, 3,...
ORDER BY 1, 2, 3,...
根据“……它可以很容易地扩展到更多的列,只要需要
SELECT SUM(NULLs) AS 'NULLS', SUM(NOTNULLs) AS 'NOTNULLs' FROM
(select count(*) AS 'NULLs', 0 as 'NOTNULLs' FROM us WHERE a is null
UNION select 0 as 'NULLs', count(*) AS 'NOTNULLs' FROM us WHERE a is not null) AS x
这很糟糕,但它将返回一个带有2个cols的记录,指示null和非null的计数。