[英]CASE WHEN to produce value based on null values
與桌子CARS
:
Make | Model | Color | Year
------- --------- ------- -----
Honda | Accord | Red | 09
Nissan | Skyline | Blue | 15
null | Skyline | Red | 15
Toyota | null | Black | 15
我試圖在Make包含一個值但Model不包含時在Make列中生成字符串ERROR 。 我的陳述目前沒有任何結果
SELECT
CASE
WHEN (SELECT Count(*)
FROM CARS
WHERE a.make=make
AND a.year=year
AND a.color=color
AND a.model = NULL) AND (SELECT Count(*)
FROM CARS
WHERE a.year=year
AND a.color=color
AND a.make = make) > 1 THEN '**ERROR**'
ELSE a.make
END as make
FROM a.CARS
如果當make沒有任何值,但model有值時,您希望將ERROR作為make的值,那么這可能是您想要的:
SELECT
CASE
WHEN make IS NULL AND model IS NOT NULL
THEN 'ERROR'
ELSE make
END AS make,
model, color, year
FROM cars;
也許我誤解了你的意圖。 您的問題似乎與您發布到其他答案的評論不同。
create table cars
(
make varchar(100) null,
model varchar(100) null,
color varchar(100) null,
year int null
);
insert cars(make,model,color,year) values ('honda','accord','red',2009);
insert cars(make,model,color,year) values ('nissan','skyline','blue',2015);
insert cars(make,model,color,year) values (null,'skyline','red',2015);
insert cars(make,model,color,year) values ('toyota',null,'black',2015);
select
(case when c.make is null then 'ERROR' else c.make end) as make,
(case when c.model is null then 'ERROR' else c.model end) as model,
c.color, c.year
from cars c;
編輯 :
select c.make,c.model,c.color,c.year,
case when ( (c.make is null and c.model is not null) or (c.model is null and c.make is not null) ) then 'ERROR' else '' end as col5
from cars c
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