What is UC_Person in this SQL UNIQUE Constraint example?

Question

SQL Server

Answer 1

What is UC_Person in this SQL UNIQUE Constraint example?

The ID, LastName pair is unique.
In general, this is an incorrect architecture - the ID counter must be unique, for example:

...
[ID] [int] IDENTITY(1,1) NOT NULL
...
CONSTRAINT [PK_Persons] PRIMARY KEY CLUSTERED ( [ID] ASC )
...

Yes, I forgot, another architectural mistake: you need to specify not the age, but the date of birth. And then in a year your data will lose relevance. It is possible like this:

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  [BirthDay] [datetime] NULL,
  [DeathDay] [datetime] NULL,
        [Age] [int] NULL AS DATEDIFF( Year, BirthDay, ISNULL( DeathDay, GETDATE())) 
         + ( SIGN ( DATEDIFF ( DAY, BirthDay, DATEADD ( YEAR, YEAR( BirthDay ) 
         - YEAR( ISNULL( DeathDay, GETDATE()) ), ISNULL( DeathDay, GETDATE())))) - 1 ) / 2
...