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
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
其他回答
以防你想把它记录在一条记录里:
select
(select count(*) from tbl where colName is null) Nulls,
(select count(*) from tbl where colName is not null) NonNulls
;-)
a为空的元素个数:
select count(a) from us where a is null;
a不为空的元素个数:
select count(a) from us where a is not null;
我通常用这个技巧
select sum(case when a is null then 0 else 1 end) as count_notnull,
sum(case when a is null then 1 else 0 end) as count_null
from tab
group by a
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;
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。