Oracle Server Technologies and the Relational Paradigm
Position the Server Technologies
There is a family of products that makes up the Oracle server technologies:
■ The Oracle Database
■ The Oracle Application Server
■ The Oracle Enterprise Manager
■ Various application development tools and languages
The Oracle Server Architecture
Access to the database is through the Oracle instance. The instance is a set of processes and memory
structures.
Client tier generates the SQL commands, and the server tier executes them.
The client tier consists of two components: the users and the user processes. The server tier has three xomponents: the server processes that execute the SQL, the instance, and the database itself.
The server processes interact with the instance, and the instance with the database.
A session is a user process in communication with a server process.
USER -------------- USER PROCESS ------ SERVER PROCESS --------- INSTANCE ----------- DATABASE
session Component server-side Components
Development Tools and Languages
Within the database, it is possible to use three languages.
SQL is used for data access, but it cannot be used for developing complete applications.
PL/SQL is a third-generation language (3GL) proprietary to Oracle. It has the usual procedural constructs (such as if-then-else and looping) and facilities for user interface design.
Java programmer should be able write code that will work with an Oracle database
All developers and administrators working in the Oracle environment must know PL/SQL. C and Java are not necessary, unless the project specifically uses them.
SQL Commands
These are the 16 SQL commands, separated into commonly used groups:
The Data Manipulation Language (DML) commands:
■ SELECT
■ INSERT
■ UPDATE
■ DELETE
■ MERGE
The Data Definition Language (DDL) commands:
■ CREATE
■ ALTER
■ DROP
■ RENAME
■ TRUNCATE
■ COMMENT
The Data Control Language (DCL) commands:
■ GRANT
■ REVOKE
The Transaction Control Language (TCL) commands:
■ COMMIT
■ ROLLBACK
■ SAVEPOINT
According to all the docs, SELECT is a DML statement. In practice, no one includes it when they refer to DML—they talk about it as though it were a language in its own right (it almost is) and use DML to mean only the
commands that change data.