1. INFORMATION_SCHEMA
is an ANSI standard set of READ-ONLY views which provide information about all
of the tables, views, columns, and procedures in a database. All RDBMS have to
provide this views and our query would work in all RDBMS (oracle, sql, mysql
etc.) On the other hand SYS schema is specific to SQL product and would have
much more details.
2. SYS objects
would be having more information related to SQL Objects rather than
INFORMATION_SCHEMA.
The INFORMATION_SCHEMA is part of the
SQL-92 standard, so we can use it in other database engines in future stage. In
SQL Server, these views exist in each database. It is not under the
"dbo" user. Instead they are under the ownership of
INFORMATION_SCHEMA. Therefore, to access any of the views, we need to preface
the view name with "INFORMATION_SCHEMA which is like below.
SELECT * FROM
INFORMATION_SCHEMA.TABLES
Each of the views in this collection
exposes a different aspect of the meta data of the database.
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