TSQL Getting the ident_current of a view this uses joins - tsql

Question

Using the following queries, I am trying to understand why I am able to get the ident_current on one view, but not the other.
Here is some sample data:
create table temptable1 (id int identity(1,1), name varchar(100), [type] int)
insert into temptable1 values
( 'apple', 1),
( 'banana', 1),
( 'cake', 3)
create table temptable2 (id int identity(1,1), name varchar(100))
insert into temptable2 values
( 'fruit'),
( 'vegetable'),
( 'pastry')
exec ('
create view dbo.identcurrentworks
as
select
t1.id as t1id
,t1.name as t1name
,t1.type as t1type
from temptable1 t1
')
--drop view dbo.identcurrentworks
exec ('
create view dbo.identcurrentdoesnotwork
as
select
t1.id as t1id,
t1.name as t1name,
t1.type,
t2.id as t2id,
t2.name as t2name
from temptable1 t1
join temptable2 t2 on t1.type=t2.id
')
--drop view dbo.identcurrentdoesnotwork
select * from dbo.identcurrentworks
select IDENT_CURRENT('dbo.temptable1')
select IDENT_CURRENT('dbo.identcurrentworks')
select * from dbo.identcurrentdoesnotwork
select IDENT_CURRENT('dbo.temptable2')
select IDENT_CURRENT('dbo.identcurrentdoesnotwork')
--drop table temptable1
--drop table temptable2
I am uncertain as to why I can get the ident_current on the view dbo.identcurrentworks but not on the other. Any ideas?

Answer 1

#Pondlife is right - the view identcurrentdoesnotwork has no identity column defined because there are two identity columns in the select statement. You can verify this by running:
sp_help identcurrentdoesnotwork
Note that as the others have pointed out, for most situations, one should use SCOPE_IDENTITY instead of IDENTITY_CURRENT.
For more on IDENT_CURRENT, click here, and for more on ##IDENTITY vs IDENT_CURRENT vs SCOPE_IDENTITY, click here .