SQL Server 2017

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CREATE TABLE TestTable
	(id nvarchar(20),Field_1 nvarchar(20),Field_2 nvarchar(20),Field_3 nvarchar(20));
INSERT INTO TestTable SELECT id= '1',Field_1 = '20' ,Field_2 =null  ,Field_3='21'
INSERT INTO TestTable SELECT id= '2',Field_1 = null   ,Field_2 =null   ,Field_3=null
INSERT INTO TestTable SELECT id= '3',Field_1 = '12' ,Field_2 ='13' ,Field_3='15'
3 rows affected

SELECT *
FROM TestTable


id
Field_1
Field_2
Field_3


1
20
null
21

2
null
null
null

3
12
13
15


select id,Field_1,Field_2,Field_3,
Field_1T+Field_2T+Field_3T as CountNull
from (
select id,Field_1,Field_2,Field_3,
case when Field_1 is null then 1 else 0 end as Field_1T,
case when Field_2 is null then 1 else 0 end as Field_2T,
case when Field_3 is null then 1 else 0 end as Field_3T
from TestTable
where 1=1
and not (Field_1 is not null
and Field_2 is not null
and Field_3 is not null)
) as TempTable
where 1=1

union
select id,Field_1,Field_2,Field_3,0 as CountNull
from TestTable
where 1=1
and Field_1 is not null
and Field_2 is not null
and Field_3 is not null
order by id


id
Field_1
Field_2
Field_3
CountNull


1
20
null
21
1

2
null
null
null
3

3
12
13
15
0

id	Field_1	Field_2	Field_3
1	20	null	21
2	null	null	null
3	12	13	15

id	Field_1	Field_2	Field_3	CountNull
1	20	null	21	1
2	null	null	null	3
3	12	13	15	0