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) as select 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’, );  Inserting into object view: insert into CUSTOMER_OV values ( 123, PERSON_TY(‘name’, ADDRESS_TY( ‘Street’, ‘City’, ‘ST’, )));

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_UPDATE instead of UPDATE on AUTHOR_PUBLISHER for each row begin … 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 Array 1.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  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 Table 1.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