Sometimes you have tables that have an identity column (SQL Server) and whatever reason you need to reseed (reset) the identity column values. This may be a result of inserting and deleting a lot of data during testing a process. It might also come up if you want to start the sequence at a different number or you backed up data and want to start it over again (like in a new year). You could create a new table and then import from the original into the new without the identity column, however; this is not necessary and a lot of extra work.
There is a way to do it without having to create, insert, drop.
For example if you want to reseed a customer table starting with 50 then your syntax would be.
DBCC CHECKIDENT ('Customer', RESEED, 50)
If just want to know what the next number is then your syntax would be.
DBCC CHECKIDENT ('Customer', NORESEED)
As you can see that whatever your seed number is the next record inserted will be the seed + 1 so in the above example the new number would be 51.
Word of Caution: It is not a good idea to reseed an identity column in a table that contains data without validating the impact of doing it.