Select Records from First OR occurence within a multiple AND/OR T-SQL statement within a function - sql

Question

I have the following SQL (example):
SET #Return_Value = = (SELECT Top 1
(CASE WHEN .... THEN ColumValue1 ELSE ColumValue2 END)
FROM TableA WHERE (Lots of AND Statements)
AND
(
(bla1)
OR
(bla2)
OR
(bla3)
)
The bla1, etc are logic to retrieve colum values from TableA. How can I return the values from bla1 if they were found without executing bla2 or bla3 because those might overwrite what I'm looking for? In other words I only want to execute OR statements if the previous one didn't find data, all this within a function.

Answer 1

You can use a case expression as :
SET #Return_Value = (SELECT Top 1
(CASE WHEN .... THEN ColumValue1 ELSE ColumValue2 END)
FROM TableA WHERE (Lots of AND Statements)
AND
( 1 = case when condition1 then 1
case when condition2 then 1
case when condition3 then 1
end
);

Answer 2

you can use order by, like
select Top 1
CASE WHEN .... THEN ColumValue1 ELSE ColumValue2 END
FROM TableA
WHERE
(Lots of AND Statements) AND
(
(bla1) OR
(bla2) OR
(bla3)
)
order by
case
when (bla1) then 1
when (bla2) then 2
when (bla3) then 3
else 999
end
Or you can try to simplify it (but you have to check performance):
select Top 1
CASE WHEN .... THEN ColumValue1 ELSE ColumValue2 END
FROM TableA
outer apply (
select
case
when (bla1) then 1
when (bla2) then 2
when (bla3) then 3
end as T
) as C
WHERE
(Lots of AND Statements) and
C.T is not null
order by C.T
or, for example, you can use union, something like this:
with cte as (
select Top 1
CASE WHEN .... THEN ColumValue1 ELSE ColumValue2 END as data
FROM TableA
WHERE
(Lots of AND Statements)
), cte2 as (
select top 1 data, 1 as c from cte where (bla1)
union all
select top 1 data, 2 as c from cte where (bla2)
union all
select top 1 data, 3 as c from cte where (bla3)
)
select top 1 data
from cte2
order by c