问题
I am trying to add case statement to where condition in a query. My query looks like below-
select * from table_name
where
if(id==1) then col1 = 0
else col1 is null
As shown in above query I want to add col1 = 0 in where condition if id-==0 else I want col1 is null in where condition. I tried
select * from table_name
where
case id =1 then (col1 = 0)
else col1 is null
end
But the syntax is incorrect. Is there any way to do this?
回答1:
SELECT *
FROM table_name
WHERE isnull(id, '')= CASE(id)
WHEN 1
THEN 0
ELSE ''
END;
回答2:
I am not sure of your requirement but you can try if below satisfies you
select * from table_name
where
isnull(col1,'') = case when id = 1 then 0
else '' end
Also try
select * from table_name
where
( col1 = 0 and id = 1) OR ( col1 is null and id<>1 )
回答3:
I think you are looking for a case when solution. Which can be used as below to fill in a specific column. You do need to select the other columns as well when you do this though.
select
case when id = 1 then 0 else null end as col1
from table_name
回答4:
I think this is what you're looking for:
select case when id = 1 then 0 else null end as col1, * from table_name
来源：https://stackoverflow.com/questions/46977510/use-case-in-where-clause