In the 1970s, IBM developed a product called SEQUEL, or Structured English
Query Language, which ultimately became SQL, the Structured Query Language.
IBM, along with other relational database vendors, wanted a standardized method
for accessing and manipulating data in a relational database. Over the decades,
many competing languages have allowed programmers and developers to access
and manipulate data. However, few have been as easy to learn and as universally
accepted as SQL.
PL/SQL lets you declare local variables and constants and then use those identifiers in your PL/SQL program.
You can declare the variables and constants to be a datatype known to the RDBMS, such as NUMBER or
VARCHAR2. However, you can also make use of PL/SQL−specific data structures such.
This guide describes database features that support applications using Large Object
(LOB) datatypes. The information in this guide applies to all platforms and does not
include system-specific information. Oracle Database Application Developer's Guide - Large Objects contains information that
describes the features and functionality of Oracle Database 10g.The database includes all of the resources you need to use LOBs in your application;
however, there are some restrictions on how you can use LOBs as described in the
The following diagram shows the type hierarchy defined in the World Wide
Web Consortium (W3C) specification Extensible Markup Language (XML)
Schema Part 2: Datatypes. These data types are used in XML schemas. This
specification defines built-in primitive data types, derived data types, and