1

Part IV: Object-Relational Databases

Ch. 30: Types, Object Views, Methods

Ch. 31: Nested Tables and Varying Arrays

Ch. 32: Large Objects

Ch. 33: Advanced OO Concepts

2

Ch. 30: Types

Abstract datatypes groups related columns/data .create type ADDRESS_TY as object( Street VARCHAR2(50), City VARCHAR2(25), State CHAR(2), Zip NUMBER);

Abstract datatypes can be nested . security – must have EXECUTE privilege to use a type. set describe depth – see attributes within an object.

3

Ch. 30: Types: indexing, selecting, manipulating

Create type PERSON_TY ( Name VARCHAR2(25), Address ADDRESS_TY);Create table CUSTOMER ( Cust_Id NUMBER, Person PERSON_TY );

Select:select c.Name, c.Person.Address.City from CUSTOMER c where c.Person.Address.City like ‘I%’;

Indexing:create index IDX_CUST on CUSTOMER(Person.Address.City);

Insert:insert into CUSTOMER values (1, PERSON_TY(‘xxxx’, ADDRESS_TY(‘aaaa’, ‘bbb’, ccc’)));

4

Ch. 30: Object Views.

create table CUSTOMER(Cust_id NUMBER PRIMARY KEY, Name VARCHAR2(25), Street VARCHAR2(50), City VARCHAR2(25), State CHAR(2), Zip NUMBER);

create type ADDRESS_TY as object( Street VARCHAR2(50), City VARCHAR2(25), State CHAR(2), Zip NUMBER);

create type PERSON_TY ( Name VARCHAR2(25), Address ADDRESS_TY);

create or replace view CUSTOMER_OV(Cust_id, person) asselect Cust_id, PERSON_TY (Name, ADDRESS_TY(street, city, state, zip))from CUSTOMER;

Inserting into original table:

insert into CUSTOMER values ( 123, ‘name’, ‘Street’, ‘City’, ‘ST’, 99999 );

Inserting into object view:

insert into CUSTOMER_OV values ( 123, PERSON_TY(‘name’, ADDRESS_TY( ‘Street’, ‘City’, ‘ST’, 99999 )));

5

Ch. 30: INSTEAD OF Triggers

Views usually cannot use standard table-based PL/SQL Triggers, but they can use INSTEAD OF triggers. Works with either normal views or object views.

create trigger AUTHOR_PUBLISHER_UPDATEinstead of UPDATE on AUTHOR_PUBLISHERfor each rowbegin …end;

6

Ch. 30: Methods

Methods allow types to have “behavior”.

Methods are declared inside CREATE TYPE, they are defined with CREATE TYPE BODY.

create type PERSON_TY ( Name VARCHAR2(25), Address ADDRESS_TY, Birthday DATE, member function AGE (BirthDate IN DATE) return NUMBER);

create or replace type body PERSON_TY as member function AGE (Birthdate DATE) return NUMBER is begin return ROUND(sysdate – Birthdate); end;

end;

7

Ch. 31: Collector: Varying Arrays Definition – a varying array is a set of objects, each of same type, seen as a

column within a table. The size is limited when created.

Creating a Varying Array1. Create type TOOL_TY as object (…);2. Create type TOOLS_VA as varray(5) of VARCHAR2(25);3. Create table TOOL_BORROWER (…, Tools TOOLS_VA);

Describing – requires queries on data dictionary to show varray structure.

Selecting – requires PL/SQL, see p. 571-572

Inserting – insert into TOOL_BORROWER values (‘name’, TOOLS_VA(‘tool1’, ‘tool2’, ‘tool3’));

Storage – stored in-line, ie. within table data segment.

8

Ch. 31: Collector: Nested Tables Definition – a nested table is a table within a table.

Their size is not limited as with varying arrays.

Creating a Nested Table1. Create type TOOL_TY as object (…);2. Create type TOOLS_NT as table of TOOL_TY;3. Create table TOOL_BORROWER (…,

nested table Tools TOOLS_NT);

Describing – set describe depth will allow the describe command to show nested tables.

Selecting – requires the TABLE() function (previous to 9i use THE() function).This “flatten’s” or de-normalizes the nested table’s relationship.

Select BreederName, N.Name, N.birthdate from BREEDER, TABLE(breeder.Animals) N

Inserting – insert into TABLE(select Animals from BREEDER where Breedername = ‘x’) values (ANIMAL_TY (‘x’,’y’,’z’));

Storage – Nested tables can be stored in or out-of-line. Recommend they be stored out-of-line with a storage clause to improves query performance.

9

Ch. 32: Large Object Datatypes

BLOB – binary field up to 4Gb.

CLOB – character field up to 4Gb.

NCLOB – CLOB that supports MBCS (multi-byte character set).

BFILE – read-only binary data stored in a file outside of the database.

10

Ch. 32: LOB Storage, Initialization

LOB Storage – BLOB and (N)CLOB columns are stored out-of-line. They require the CREATE TABLE statement include a LOB STORAGE clause to tell where the LOB segment is stored. BFILE columns are by their nature stored out-of-line.

LOBs use at least 1 entire data block per row in the LOB segment. Normal DATA segments store multiple rows per block (up to 100% -PCTFREE).

Initializing LOBs – use EMPTY_BLOB or EMPTY_CLOB instead of NULL to initialize a LOB. • NULL will create a LOB with no data.• EMPTY_BLOB/CLOB will create an empty “LOB locater” (pointer)

without allocating the empty block.

11

Ch. 32: DBMS_LOB LOB data is manipulated with the DBMS_LOB package.

For all LOBs:• APPEND• COMPARE• COPY • ERASE • GETCHUNKSIZE• GETLENGTH• INSTR• ISOPEN• OPEN• READ• SUBSTR• TRIM• WRITE• WRITEAPPEND

BFILE specific functions: • FILEOPEN• FILECLOSE• FILECLOSEALL• FILEEXISTS• FILEGETNAME• FILEISOPEN• LOADFROM FILE

Temporary LOB functions:• CREATETEMPORARY• FREETEMPORARY• ISTEMPORARY

12

Ch. 32: BFILE Read-only binary data stored in a file outside of the database.

CREATE DIRECTORY PROPOSAL_DIR AS ‘C:\My Documents’;

Insert into thetable ( col1, bfilecol ) values ( ‘value1’, BFILENAME(‘proposal_dir’, ‘myfile.doc’);

Deleting LOBs – internal LOBs when deleted have both their data and LOB locater deleted. Deleting a BFILE only deletes the locater, the file is read only and thus not changed.

13

Ch. 33: row objects vs. column objects

Row objects

Column objects

14

Ch. 33: REF, DEREF, VALUE

REF

DEREF

VALUE