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
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;
其他回答
所有的答案要么是错误的,要么是非常过时的。
执行此查询的简单而正确的方法是使用COUNT_IF函数。
SELECT
COUNT_IF(a IS NULL) AS nulls,
COUNT_IF(a IS NOT NULL) AS not_nulls
FROM
us
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
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。
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
;-)
select count(isnull(NullableColumn,-1))