Tsql can't update the column with count statement

Question

declare @t1 Table
(
a1 int
)

insert into @t1 
select top 10 AnimalID from Animal 

--select * from @t1 

declare @t2 table
(
dogs int null
)

update @t2
set dogs = (Select COUNT(*) from @t1)

---------> The out put it gives me is just 0

Answer 1

Try using an insert statement instead of an update ("update" is to modify an already existing record; "insert" is to enter a new one) -

INSERT INTO @t2 SELECT COUNT(*) FROM @t1

And why should there be any output at all from this code? I don't see any select or print statements.

(What exactly are you trying to accomplish?)

Answer 2

It's because you never insert into @t2, so your update doesn't have any records to update.

Answer 3

well first you can't update any records in @t2 becasue you don't have any records to update. You need to do another insert. Assuming you had records, you need a way to relate the subquery to the record you need to update which you don't have.

Answer 4

It is because you are creating your table, and updating it, but its empty.

Change

update @t2 set dogs = (Select COUNT(*) from @t1)

For

declare @c int

select @c = COUNT(*) from @t1

insert into @t2 (dogs) values (@c)