Oracle PL/SQL - Glossary

Aggregation

Aggregation occurs where one object is composed, at least in part, of other objects; you may call it a part-of relationship. A tail is a part-of a dog or a piston is a part-of an engine. This concept is implemented within collections.

API

Application Programming Interface: An API is designed to allow quick and easy integration of different programming languages like C, Java, and so on, with the Oracle 8i database and its development environment.

BLOB

Binary Large Objects, a LOB whose value is composed of unstructured binary ("raw") data.

Client-side object cache

The object cache is a client-side memory buffer that provides lookup and memory management support for objects. It stores and tracks object instances that have been fetched by an OCI application. When objects are fetched by the application through a SQL SELECT, or through an OCI pin operation, a copy of the object is stored within the object cache.

CLOB

Character Large Object, a LOB whose value is composed of character data that corresponds to the database character set defined for the Oracle8 database.

Composition

A composition embodies the concept of a column within a table is a combination of several composite columns. This concept cannot be handled within a relational database. In Oracle8i, it is possible with object types and collections such as varrays and nested table.

Constraint

Use a constraint to define an integrity constraint, a rule that restricts the values in a database. Oracle Database lets you create six types of constraints and lets you declare them in two ways.

Constructor

Every time a user-defined data type is created, Oracle generates a method called the constructor method, which is a system-defined method. When invoked, the constructor method creates a new object based on the specification of the object type. Oracle names the new constructor method the same name as the new object type. The parameters are the same as the attributes named within the object type definition.

Correlation argument

A correlation argument is a parameter, which is passed when a function is used, e.g. the VALUE finction requires the table alias to be passed as a parameter or correlation argument.

Correlation variable

A correlation variable is a parameter, which is passed when a function is used, e.g. the VALUE finction requires the table alias to be passed as a parameter or correlation variable.

DBMS_LOB

The DBMS_LOB package provides subprograms to operate on BLOBs, CLOBs, NCLOBs, BFILEs, and temporary LOBs. You can use DBMS_LOB to access and manipulate specific parts of a LOB or complete LOBs.

DML

Data Manipulation Language. INSERT, UPDATE, and DELETE statements are DML statements.

Dot notation

To reference individual fields within the record, use the dot notation. A dot (.) serves as the selector for the individual field name.

Encapsulation

Encapsulation is the concept of information hiding. Encapsulation asserts that you can only "get at" the contents of the object using predefined functions. This allows the programmer to retain control of the data and helps reduce the impact on changes to the schema.

Enumeration

An enumeration is a data type which can be given a finite (usually small) set of named values. Therefore, enumerations are useful for representing real world values that naturally have a finite set of values, each of which has a meaningful name.

Flattening

A relational table which is associated with a nested table consists of two tables, the main relational table and the nested table. To query, update, insert, or to delete records from the nested table, it must be queried as if it were a single table. This is achieved by the usage of "THE" or "TABLE" functions.

Glossary

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Homogenous

Homogenous means elements of the same data type.

Inheritance

Inheritance is a technique used within object-oriented development to create objects that contain generalized attributes and behavior for groups of related objects. The more general objects created using inheritance are referred to as super-types. The objects that "inherit" from the super-types (that is, they are more specific cases of the super-type) are called subtypes.

LOB

Large Objects are data types defined within Oracle 8i. They are used for storing upto 4 GB of data.

LOBFiles

LOBFILES are relatively simple datafiles that facilitate LOB loading. The attribute that distinguishes LOBFILEs from the primary datafiles is that there is no concept of a record within LOBFILES.

NCLOB

National Character Large Object, a LOB whose value is composed of character data that corresponds to the national character set defined for the Oracle8 database.

Object-relational

The object-relational model allows users to define object types, specifying both the structure of the data and the methods of operating on the data, and to use these datatypes within the relational model.

OCI

Oracle Call Interface. The general goal of an OCI application is to operate on behalf of multiple users. Within an n-tier configuration, multiple users send HTTP requests to the client application. The client application may need to perform some data operations that include exchanging and performing data processing.

Persistent object

An object that is stored or saved. Within Oracle, an object is stored within the database.

Persistent store

Persistent store is a database that has all the persistent data.

Pinning

Pinning is the process of retrieving an object from the server to the client cache, laying it within memory, providing a pointer to it for an application to manipulate, and marking the object as being in use.

Pre-delete trigger

A pre-delete trigger is a trigger which is fired before a record is deleted from a table.

REPLACE

CREATE OR REPLACE is the syntax for creating procedures, functions, or object types. It means that if the object type / procedure already exists within the database, the DDL statement should replace the existing object type / procedure.

Secondary Data Files

Secondary-Data-File are files similar in concept to the primary datafiles. Like primary datafiles, SDFs are a collection of records and each record is made up of fields. The SDFs are specified on a per control-file-field basis.

Sparse

Sparse means lesser number of elements or records.

SQL*Loader

This is a utility provided by Oracle to load data from text files into the Oracle database.

Subtype

A type that extends another type by adding attributes and/or methods. For example, a fox is a special case of a mammal.

Supertype

A type that is extended by another type. A supertype may have one or more derived types that inherit its attributes and methods. For example, a mammal is a supertype of fox.

Tablespace

A database is divided into logical storage units called tablespaces, which group related logical structures together. For example, tablespaces commonly group all the objects of an application to simplify some administrative operations.

Transient object

A transient object is an instance of an object type. It may have an object identifier, and it has a lifetime which is determined by the application when the instance is created. The application can also delete a transient object at any time. Transient objects are often created by the application to store temporary values for computation. Transient objects cannot be converted to persistent objects. Their role is fixed at the time they are instantiated.

Wrapped

Insert definition here.

Zero-Byte Fillers

While editing or copying on an existing LOB, if the data already exists at the start position of the destination, it is overwritten with the source data. If the start position of the destination is beyond the end of the current data, zero-byte fillers (for BLOBs) or spaces (for CLOBs) are written into the destination LOB from the end of the current data to the beginning of the newly written data from the source.