If you add the UNIQUE constraint on a column, SQL Server will automatically add a non-clustered index for that column. The tutorial exercise below shows you the index created as part of the UNIQUE column, "id", of "ggl_links":

USE GlobalGuideLineDatabase;

GO

-- Drop the old table, if needed

DROP TABLE ggl_links;

GO

-- Create a table with a UNIQUE constraint

CREATE TABLE ggl_links (

id INT UNIQUE,

url VARCHAR(80) NOT NULL,

notes VARCHAR(1024),

counts INT,

created DATETIME NOT NULL DEFAULT(getdate())

);

GO

-- Create an index for column "url"

CREATE INDEX ggl_links_url ON ggl_links (url);

GO

-- View indexes

EXEC SP_HELP ggl_links;

GO

index_name   index_description   keys

----------------------- -------------------------- ----

ggl_links_url  nonclustered located  url

     on PRIMARY

UQ__ggl_links__4222D4EF nonclustered, unique

     key located on PRIMARY id

Notice that the index created as part of the UNIQUE constraint is named by SQL Server as "UQ__ggl_links__4222D4EF".