SQL Server - How to insert a record and make sure it is unique

Question

I\'m trying to figure out the best way to insert a record into a single table but only if the item doesn\'t already exist. The KEY in this case is an NVARCHAR(400) field. Fo

Answer 1

while unique constraint is certaily one way to go you can also use this for your insert logic: http://www.sqlteam.com/article/application-locks-or-mutexes-in-sql-server-2005

basicaly you don't put any locks on the table below thus not worrying about the reads while your existance checks will be performed ok.

it's a mutex in sql code.