如何让我的 t-sql 代码检查条件然后停止？不检查下一个条件。返回应该只有一个结果

Question

伪：
如果条件为真，则返回结果并且不寻找下一个条件。 如果条件为假，则检查下一个条件。 等等...我有大约 6 个要按层次结构顺序检查。

案例检查每个条件，因此它不会在第一个条件处停止，而是继续，并且集合中有多个 true，但是，我只想要第一个！

Nest IFF 也给了我同样的东西。 （多个答案）

IIF((t.testkey = 141  AND wordsalad <3) OR (t.testkey = 141 AND wordsalad>10),'Found it 1',
iif(t.testkey = 821 AND wordsalad <20,'Found it 2',
    iif(t.testkey = 725 AND wordsalad<1.0030,'Fouind it 3',
        iif(t.testkey = 725 AND wordsalad>1.025,'Found it 4',
            iif(t.testkey = 810 AND wordsalad<10,'Found it 5',
                iif(t.testkey = 809 AND word salad<10,'found it 6',
                    'Didn't find it')))))),

我该如何编写，以便它在找到第一个条件后停止而不继续？

这是针对案例：

CASE
WHEN (t.testkey = 141 AND wordsalad <3) OR (t.testkey = 141  AND 
wordsalad >10.0)) then 'Found it 1'
WHEN (t.testkey = 821 AND wordsald <20) then 'Found it 2'
WHEN (t.testkey = 725 AND wordsalad <1.0030) then 'Found it 3'
WHEN (t.testkey = 725 AND wordsalad >1.025) then 'Found it 4'
WHEN (t.testkey = 810 AND wordsalad <10) then 'Found it 5'
WHEN (t.testkey = 809 AND wordsalad <10) then 'Found it 6'
Else 'Didn't find it'
END AS [Conditions2]

数据看起来像这样：

Test | TestKey    | wordsalad | 
Test1| TestKey141 | 10.2      |
Test2| TestKey821 | 4         |
test3| TestKey725 | 0         |

等等..

Answer 1

我有点猜测你到底在追求什么，但也许是这样的（？）：

create table sometable (id int, testkey int, wordsalad decimal(18,6))

insert sometable (id, testkey, wordsalad) values (1, 821, 17)
insert sometable (id, testkey, wordsalad) values (1, 725, 0.5)
GO

-- return the row that matches the most preferred condition. 
-- If none of the rows matched any of the conditions, then no row is returned.

select top 1 * from sometable t
cross apply (
select 
CASE
WHEN (t.testkey = 141 AND wordsalad <3) OR (t.testkey = 141  AND 
wordsalad >10.0) then 1  -- most preferred condition
WHEN (t.testkey = 821 AND wordsalad <20) then 2
WHEN (t.testkey = 725 AND wordsalad <1.0030) then 3
WHEN (t.testkey = 725 AND wordsalad >1.025) then 4
WHEN (t.testkey = 810 AND wordsalad <10) then 5
WHEN (t.testkey = 809 AND wordsalad <10) then 6  -- least preferred condition
Else NULL -- not matched
END AS cond
) c
where c.cond IS NOT NULL
order by c.cond