Ident_Current('TableName') not giving last inserted identity Value in SQL Server 2012

Question

Hi ,
Ident_Current('TableName') is not giving last inserted identity Value in SQL Server 2012. 
Latest Value of ID and Ident_Current is differing for that particular table.  
Why its happening? Ident_Current value is greater than last inserted ID.
Please guide me why its happening?

Answer 1

Here is one example:
CREATE DATABASE PMCtest ON (NAME = 'PMCtest', FILENAME = 'B:\ProdDB-Unzipped\PMCtest.mdf', SIZE = 25GB )
LOG ON (NAME = 'PMCtest_log', FILENAME = 'B:\ProdDB-Unzipped\PMCtest.ldf', SIZE = 2GB)
CREATE TABLE identity_crisis (a int IDENTITY NOT NULL PRIMARY KEY,
                              b sysname NOT NULL CHECK (b <> 'sysschobjs'))
go
INSERT identity_crisis (b) VALUES ('First name')
INSERT identity_crisis SELECT name FROM sys.objects
go
SELECT MAX(a), ident_current('identity_crisis')
FROM  identity_crisis
go
DROP TABLE identity_crisis
Because the second INSERT statement fails, the identity values from 2 to 12 are lost. This is a very intentional design to promote high concurrency. If you don't want gaps, you should not use IDENTITY, but roll your own.
Also, beware that ident_current returns database-wide value, so if you insert one row, and another process inserts another row before you interrogate ident_current, you will get the id for the row of the other process.
Erland Sommarskog, SQL Server MVP, [email protected]