Unlike access languages for non-relational databases, using SQL for queries has several important features. Being declarative,
the person who writes an SQL statement is not concerned about how the Oracle engine will service the query.
That is, the programmer is not concerned about whether Oracle uses an index , performs a hash join, or does a full-table scan against the table.
The Oracle engine takes care of figuring out the optimal way to access the data when the SQL statement is executed.
These extensions are unique to Oracle SQL.
Applications that are written to be portable between databases must not use any of the vendor-supplied extensions.
The portable SQL application system is specifically designed to be generic so it can be moved between relational database products without re-writing the SQL statements.
For those of you who have asked the question:
These extensions are very helpful in quickly retrieving and formatting data, but they also have
drawbacks to the database
We will exam ANSI standards in more detail later in the course.
In the next lesson, the basic tools for Oracle tuning will be discussed.