@@IDENTITY vs SCOPE_IDENTITY() vs IDENT_CURRENT

SELECT @@IDENTITY
It returns the last IDENTITY value produced on a connection, regardless of the table that produced the value, and regardless of the scope of the statement that produced the value.
@@IDENTITY will return the last identity value entered into a table in your current session. While @@IDENTITY is limited to the current session, it is not limited to the current scope. If you have a trigger on a table that causes an identity to be created in another table, you will get the identity that was created last, even if it was the trigger that created it.

SELECT SCOPE_IDENTITY()
It returns the last IDENTITY value produced on a connection and by a statement in the same scope, regardless of the table that produced the value.
SCOPE_IDENTITY(), like @@IDENTITY, will return the last identity value created in the current session, but it will also limit it to your current scope as well. In other words, it will return the last identity value that you explicitly created, rather than any identity that was created by a trigger or a user defined function

SELECT IDENT_CURRENT(’tablename’)
It returns the last IDENTITY value produced in a table, regardless of the connection that created the value, and regardless of the scope of the statement that produced the value.
IDENT_CURRENT is not limited by scope and session; it is limited to a specified table. IDENT_CURRENT returns the identity value generated for a specific table in any session and any scope.


Example query to understand

--/********create a table*************/
create table TB_01(id int identity(1,1),name varchar(50))

--/********create another table*************/
create table TB_02(id int identity(1,1),name varchar(50))

--/***create a Procedure to insert value into table1 and printing the last inserted identity value******/
create procedure sp_01
(@nam varchar(50))
as
begin
declare @ident varchar(50);
insert into TB_01([name]) values(@nam)
select @ident=@@identity;
print @ident
end


--/********create a trigger to insert in table 2 while inserting in table 1*************/
create trigger trg01 on TB_01
after insert
as
begin
insert into TB_02([name]) select [name] from inserted
end

select * from TB_01


exec sp_01 'jayaraman'