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Posted by Erland Sommarskog on 08/27/05 01:13
(wackyphill@yahoo.com) writes:
> I know in SQL Server the terms Database and Catalog are used
> interchangably. But a table is also assigned a schema. As seen in the
> INFORMATION_SCHEMA.Tables View. I don't get what this schema qualifier
> is all about. Like if a table has a schema of dbo.
>
> Can someone explain the relationship the schema has and what it is?
See schema as a way of categorising the objects in a database. This can
be a good thing if several apps share a database, and while there is some
common set of data that all apps accesses, some applications also have
their own private tables. In this case it is a good idea to have a
separate schema for each application where they can have their private
tables, views, stored procedures etc to evade the disk for collisions.
Now, in SQL 2000, there is a serious restriction in that a schema is
tied to a user. In fact, it makes schema virtually useless. But this
changes in SQL 2005 where users have been separated from schemas.
Finally, the schema in INFROAMTION_SCHEMA is a slightly different
usage. Sometimes uses "schema" to refer some set of tables, possibly
all tables in the database. SQL 2000 even has a CREATE SCHEMA command
for creating several tables in one go.
--
Erland Sommarskog, SQL Server MVP, esquel@sommarskog.se
Books Online for SQL Server SP3 at
http://www.microsoft.com/sql/techinfo/productdoc/2000/books.asp
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