Clarification on the limitation of sequence generator in T-SQL

Question

Hi, I found this limitation of sequence numbers for T-SQL:
"If there are multiple instances of the NEXT
VALUE FOR function specifying the same sequence generator within a single Transact-SQL statement, all those instances
return the same value for a given row processed by that Transact-SQL statement. This behavior is consistent with the ANSI standard."
From this link:  http://technet.microsoft.com/en-us/library/ff878058.aspx
Does this mean that if we want to have different value generated then we can't use it in multi-threading environment whereby multiple instances / processes are calling the same T-SQL code that generate the sequence numbers using the
NEXT VALUE FOR function?
My understanding of the above might not be correct, any sample example to illustrate this limitation? 
Thanks

Answer 1

Hi
This is the meaning of the comment in the article.
If you are using in a single t-sql
statement several times (NEXT VALUE FOR) then it will act as you use the same value. This is in-design :-)
try this for example:
select (NEXT VALUE FOR MySequenceName),(NEXT VALUE FOR MySequenceName),(NEXT VALUE FOR MySequenceName) -- same value several times
But you can use (NEXT VALUE FOR) several time like this:
DECLARE @QQ_01 int, @QQ_02 int, @QQ_03 int, @QQ_04 int
SET @QQ_01 = NEXT VALUE FOR MySequenceName;
SET @QQ_02 = NEXT VALUE FOR MySequenceName;
SET @QQ_03 = NEXT VALUE FOR MySequenceName;
SET @QQ_04 = NEXT VALUE FOR MySequenceName;
SELECT @QQ_01,@QQ_02,@QQ_03,@QQ_04 -- different valus
Hope this clarify things :-)
[Personal Site] [Blog] [Facebook]