Learn how to create, drop, and manage a unique constraint using SQL and some best practices to follow. A unique constraint prevents data duplication and ensures data integrity.

Learn how to drop an index in SQL Server using T-SQL or SSMS, what to consider before dropping an index, and how to monitor the effects on your database.

According to the ANSI standards SQL:92, SQL:1999, and SQL:2003, a UNIQUE constraint should disallow duplicate non-NULL values, but allow multiple NULL values. SQL Server has always implemented a ...