creating a new numbered column as primary key in a table

[chrispycrunch]

This is a fairly simple question, but what is the easiest way to:

create a new numbered column (where value is simply the row number) in
an existing table and setting it as a primary key?

[David Portas]

There is no such thing as a "row number" in SQL Server. The easiest way
to add an arbitrary, unique number to a table is to add an IDENTITY
column. You can then add a primary key constraint to that column if you
wish.

There is no point making IDENTITY the *only* key in a table though. You
should also declare a unique constraint on some other column(s) too. If
you have existing duplicates in the table then IDENTITY can help you
clean up the data by giving you a unique key to delete against.

--
David Portas
SQL Server MVP
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