Database Reference
In-Depth Information
the last 20 years. Here is an example of a query (a question posed to the
database that asks for certain information) written in SQL:
SELECT NAME, STREET, CITY, COUNTRY
FROM ARTIST
WHERE COUNTRY IN ('USA','Canada');
1.3.2
What Is Oracle SQL?
Like many other relational database products, Oracle SQL is a proprietary
and exclusive form of SQL written for Oracle Database. ANSI standards
are generally adhered to. Most database vendors have specific characteris-
tics within their exclusive versions of SQL, and Oracle Corporation is no
exception.
Oracle SQL consists of three essential parts:
SELECT . The SELECT statement is used to retrieve data from Ora-
cle Database objects such as tables, views, or clusters.
DML . The Data Manipulation Language (DML) changes data in
tables in a database. Commands included are INSERT, UPDATE,
DELETE, and MERGE. All DML commands are subject to transac-
tional control. Transactional control includes the COMMIT and
ROLLBACK commands, which allow changes to be permanently
stored or undone, respectively.
DDL . The Data Definition Language (DDL) allows changes to “def-
initional” data or metadata. Metadata is the data about the data.
Metadata is the definition of data objects such as tables along with
their column names, sizes, and data types of those column names. In
some relational databases, DDL-type commands can be undone
using a ROLLBACK command, but not in Oracle Database. DDL
commands cannot be committed or rolled back because they are
automatically and forcibly committed (permanently changed).
1.3.2.1
ANSI Standards and Oracle
The standard format of SQL was developed by the American National
Standards Institute (ANSI ). ANSI works with companies like Oracle Cor-
poration to develop its standards, thus helping to gain support among com-
petitors for a unified standard that benefits everyone.
 
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