Creating a computed column in SQL Server 2008

问题:

I have a SQL Server 2008 database. This database has a Table called "Book". "Book" has the following properties:

• ID (int)
• Title (nvarchar(256))
• PublishDate (datetime)

I need to create a computed column called "AgeInMinutes". I'm not very familiar with computed columns. I understand the concept, but I'm not sure how to do it. In SQL Server Management studio, in the "Column Properties" area, I see a property called "(Formula)" in the Table Designer section. I assume I need to enter my calculation here. However, I'm not sure what to put here. Can somebody please help me?

Thank you!

回答1:

You can define the column in your CREATE TABLE as:

AgeInMinutes as (DATEDIFF(minute, PublishDate, GETDATE())

Alternatively, just do

ALTER TABLE Book
ADD AgeInMinutes as (DATEDIFF(minute, PublishDate, GETDATE())

回答2:

Modify computed column through SSMS. Right click on table and select Design then click on computed column then see in column properties there is one option like. Computed column specification there you can alter COMPUTED COLUMN.