select exists

is it possible to select EXISTS directly as a bit?

Question : I was wondering if it's possible to do something like this (which doesn't work):

select cast( (exists(select * from theTable where theColumn like 'theValue%') as bit)

Seems like it should be doable, but lots of things that should work in SQL don't ;) I've seen workarounds for this (SELECT 1 where... Exists...)

but it seems like I should be able to just cast the result of the exists function as a bit and be done with it.

Answer:

If you must return a conditional bit 0/1 another way is to:

SELECT CAST(
   CASE WHEN EXISTS(SELECT * FROM theTable where theColumn like 'theValue%') THEN 1 
   ELSE 0 
   END 
AS BIT)

Or without the cast:

SELECT
   CASE
       WHEN EXISTS( SELECT 1 FROM theTable WHERE theColumn LIKE 'theValue%' )
            THEN 1 
       ELSE 0 
   END

参考资料:

sql - is it possible to select EXISTS directly as a bit? - Stack Overflow

　　Subqueries in Google Standard SQL | Cloud Spanner | Google Cloud

　　MySQL Exists - javatpoint

exists mysql