There is little evidence that the sql community understands the
concept of a table as a variable let alone its significant
implications. Yet there is ample evidence that the sql community
thinks that it is practicing relational principals within an sq
database. This would seem an awkward state of affairs given that the
concept of table types and variables lies at the heart of a relational
database.
Every table created is at inception a table variable. There is
nothing to be done additionally to a table to change it to a
variable. This is a basic concept in a relational database. And
understanding this should lead to the idea that operating on a table
variable is significantly different than operating on a table that
is...well not a variable

I have therefore written a no nonsense and straightforward
article to clearly present the idea of a table as a variable.

http://beyondsql.blogspot.com/2007/0...variables.html

I do hope it helps.

best,
steve