How to use sequence in MS sql server?

Question

In Oracle DB we use sequence like that:
SequenceImpl s = new SequenceImpl("customer_seq", getDBTransaction());
Integer next = (Integer)s.getData();
setId(new Number(next.intValue()));
But there is no sequence in sql server ,how can I do?
Thank you~~

Answer 1

MS SQLServer have a IDENTITY column property and UNIQUEIDENTIFIER data type that is somewhat similar to Oracle's sequence. I don't know whether your table contain either of these, or you just want to set sequential number to a column.
Below is some info about IDENTITY and UNIQUEIDENTIFIER you may already know since they are in SQLServer Book.
IDENTITY property: You can define IDENTITY property on a numeric column. You can set the seed and increment on this column property very much like Oracle's sequence. The only thing I think it does not have is the "nextval". You can use IDENT_CURRENT function or @@IDENTITY after an INSERT or SELECT INTO to get the last value generated. Of course you can use this value and add the increment to get the next
value but it not the same as seqname.nextval which keep incrementing each time you call it. Getting the current identity value and adding the increment your self will not work for multiple sessions with pending
insert. Another thing about column with IDENTITY property is that you cannot insert value into this column (i.e, omit it in your insert statement values) unless IDENTITY_INSERT is on, but only one table in a
session can have IDENTITY_INSERT to be turned on.
If you don't need to know the next seq value, then IDENTITY work similar to Oracle sequence. Execute select after postchanges or commit will have system generated values. If you need to get next value before insert, Sung suggest using SEQ_TABLE and managing the next value (write a database function to mimic Oracle'
s nextval).
UNIQUEIDENTIFIER datatype: UNIQUEIDENTIFIER is a 16-byte hexadecimal number indicating a globally unique identifier (GUID). The GUID is useful when a row must be unique among many other rows. You could use NEWID() to create a value of type uniqueidentifier or calling some API function that returns a GUID. The advantage of using uniqueidentifier is that the values generated by NEWID function or application GUID are guaranteed to be unique throughout the world. The disadvantage of using uniqueidetifier is that it is long and obscure, random, difficult for user to remember or type correctly. It is 16 byte, which is large compare to other datatype such as 4-byte integer.
Thanks,
Yvonne