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    L14 l15  oo dbms L14 l15 oo dbms Presentation Transcript

    • Rushdi Shams, Dept of CSE, KUET Database SystemsDatabase Systems Object Oriented DatabaseObject Oriented Database Management SystemsManagement Systems Version 1.0Version 1.0
    • Rushdi Shams, Dept of CSE, KUET Object- TheoryObject- Theory  An object is a package of data and procedures.An object is a package of data and procedures.  Data is contained in attributes of an objectData is contained in attributes of an object  Procedures are defined in methods of an objectProcedures are defined in methods of an object
    • Rushdi Shams, Dept of CSE, KUET Object- TheoryObject- Theory Concept of ClassConcept of Class
    • Rushdi Shams, Dept of CSE, KUET Objects- TheoryObjects- Theory Concepts of ObjectsConcepts of Objects
    • Rushdi Shams, Dept of CSE, KUET Object Types in OracleObject Types in Oracle Concept of ClassConcept of Class
    • Rushdi Shams, Dept of CSE, KUET Objects in OracleObjects in Oracle  When you create a variable of an object type,When you create a variable of an object type, you create an instance of the type and the resultyou create an instance of the type and the result is an objectis an object  An object has the attributes and methodsAn object has the attributes and methods defined for its typedefined for its type  an object instance is a concrete thing, you canan object instance is a concrete thing, you can assign values to its attributes and call itsassign values to its attributes and call its methodsmethods
    • Rushdi Shams, Dept of CSE, KUET Objects in OracleObjects in Oracle rushdirushdi person_typ;person_typ; will create an object named rushdi of typewill create an object named rushdi of type person_typ.person_typ.
    • Rushdi Shams, Dept of CSE, KUET Question at the stageQuestion at the stage  How the property ENCAPSULATION reflectsHow the property ENCAPSULATION reflects in OODM?in OODM?  What is the difference between object type andWhat is the difference between object type and object in Oracle?object in Oracle?  What is the relation between Oracle’s objectWhat is the relation between Oracle’s object type and OOP’s class?type and OOP’s class?
    • Rushdi Shams, Dept of CSE, KUET Object Type is a Data Type!Object Type is a Data Type!  Defining an object type does not allocate anyDefining an object type does not allocate any storagestorage  After they are defined, object types can be usedAfter they are defined, object types can be used in SQL statements in most of the same placesin SQL statements in most of the same places you can use types like NUMBER oryou can use types like NUMBER or VARCHAR2VARCHAR2
    • Rushdi Shams, Dept of CSE, KUET Object Type is a Data Type!Object Type is a Data Type!
    • Rushdi Shams, Dept of CSE, KUET Question at the stageQuestion at the stage  ““An object type is a data type”- justify theAn object type is a data type”- justify the answer.answer.
    • Rushdi Shams, Dept of CSE, KUET Object Methods in OracleObject Methods in Oracle  Methods are functions or procedures that youMethods are functions or procedures that you can declare in an object type definition tocan declare in an object type definition to implement behavior that you want objects ofimplement behavior that you want objects of that type to performthat type to perform  The general kinds of methods that can beThe general kinds of methods that can be declared in a type definition are:declared in a type definition are: 1.1. MemberMember 2.2. StaticStatic 3.3. ConstructorConstructor
    • Rushdi Shams, Dept of CSE, KUET Member MethodsMember Methods  Member methods are the means by which anMember methods are the means by which an application gains access to an object instance's dataapplication gains access to an object instance's data  You define a member method in the object type forYou define a member method in the object type for each operation that you want an object of that type toeach operation that you want an object of that type to be able to performbe able to perform
    • Rushdi Shams, Dept of CSE, KUET Static MethodsStatic Methods  Static methods are invoked on the object type,Static methods are invoked on the object type, not its instancesnot its instances  You use a static method for operations that areYou use a static method for operations that are global to the type and do not need to referenceglobal to the type and do not need to reference the data of a particular object instancethe data of a particular object instance  A static method has no SELF parameterA static method has no SELF parameter
    • Rushdi Shams, Dept of CSE, KUET Static MethodsStatic Methods  You invoke a static method by using the dotYou invoke a static method by using the dot notation to qualify the method call with thenotation to qualify the method call with the name of the object type, such as:name of the object type, such as: type_name.method()type_name.method()
    • Rushdi Shams, Dept of CSE, KUET Constructor MethodsConstructor Methods  Every object type has a constructor method implicitlyEvery object type has a constructor method implicitly defined for it by the systemdefined for it by the system  A constructor method is a function that returns a newA constructor method is a function that returns a new instance of the user-defined type and sets up the valuesinstance of the user-defined type and sets up the values of its attributesof its attributes
    • Rushdi Shams, Dept of CSE, KUET Questions at the StageQuestions at the Stage  What are the three methods that can be declaredWhat are the three methods that can be declared in object type definition?in object type definition?  What is the difference between static methodWhat is the difference between static method and member method?and member method?  What is the speciality about constructor method?What is the speciality about constructor method?
    • Rushdi Shams, Dept of CSE, KUET Inheritance- TheoryInheritance- Theory  A type hierarchy is a sort of family tree of objectA type hierarchy is a sort of family tree of object typestypes  It consists of a parent base type, called a superIt consists of a parent base type, called a super typetype  one or more levels of child object types, calledone or more levels of child object types, called subtypessubtypes  Child object types are derived from parentChild object types are derived from parent object classobject class
    • Rushdi Shams, Dept of CSE, KUET Inheritance- TheoryInheritance- Theory  A subtype becomes a specialized version of theA subtype becomes a specialized version of the parent type by adding new attributes andparent type by adding new attributes and methods to the set inherited from the parent ormethods to the set inherited from the parent or by redefining methods it inheritsby redefining methods it inherits  Redefining an inherited methods gives a subtypeRedefining an inherited methods gives a subtype its own way of executing the methodits own way of executing the method
    • Rushdi Shams, Dept of CSE, KUET Inheritance- TheoryInheritance- Theory
    • Rushdi Shams, Dept of CSE, KUET Inheritance- TheoryInheritance- Theory
    • Rushdi Shams, Dept of CSE, KUET PolymorphismPolymorphism  Add to this that an object instance of a subtypeAdd to this that an object instance of a subtype can generally be substituted for an objectcan generally be substituted for an object instance of any of its supertypes in code, andinstance of any of its supertypes in code, and you have polymorphismyou have polymorphism
    • Rushdi Shams, Dept of CSE, KUET Final & Not Final- TypesFinal & Not Final- Types  The definition of an object type determines whetherThe definition of an object type determines whether subtypes can be derived from that typesubtypes can be derived from that type  To permit subtypes, the object type must be defined asTo permit subtypes, the object type must be defined as not finalnot final
    • Rushdi Shams, Dept of CSE, KUET Final & Not Final- TypesFinal & Not Final- Types  By default, an object type is declared as final andBy default, an object type is declared as final and subtypes cannot be derived from itsubtypes cannot be derived from it  You can change a final type to a not final type and viceYou can change a final type to a not final type and vice versa with an ALTER TYPE statementversa with an ALTER TYPE statement  You can alter a type from NOT FINAL to FINALYou can alter a type from NOT FINAL to FINAL only if the target type has no subtypesonly if the target type has no subtypes
    • Rushdi Shams, Dept of CSE, KUET Final & Not Final- MethodsFinal & Not Final- Methods  Methods can also be declared to be final or notMethods can also be declared to be final or not finalfinal  If a method is declared to be final, subtypesIf a method is declared to be final, subtypes cannotcannot overrideoverride it by providing their ownit by providing their own implementationimplementation  Unlike types, methods are not final by defaultUnlike types, methods are not final by default and must be explicitly declared to be finaland must be explicitly declared to be final
    • Rushdi Shams, Dept of CSE, KUET Final & Not Final- MethodsFinal & Not Final- Methods
    • Rushdi Shams, Dept of CSE, KUET Inheritance- OracleInheritance- Oracle Creating SubtypeCreating Subtype
    • Rushdi Shams, Dept of CSE, KUET Inheritance- OracleInheritance- Oracle Creating Subtype of subtypeCreating Subtype of subtype
    • Rushdi Shams, Dept of CSE, KUET Questions at the StageQuestions at the Stage  What are the mechanisms Oracle use to reflectWhat are the mechanisms Oracle use to reflect the INHERITANCE of object orientedthe INHERITANCE of object oriented architecture?architecture?  What is the significance of FINAL and NOTWhat is the significance of FINAL and NOT FINAL?FINAL?  What is the difference of FINAL and NOTWhat is the difference of FINAL and NOT FINAL in case of object types and methods?FINAL in case of object types and methods?
    • Rushdi Shams, Dept of CSE, KUET Method Overriding- TheoryMethod Overriding- Theory  An method is said overriding if the methodAn method is said overriding if the method name is same for all the objects but the objectsname is same for all the objects but the objects define how the method works according to theirdefine how the method works according to their convenience.convenience.
    • Rushdi Shams, Dept of CSE, KUET Method Overriding- OracleMethod Overriding- Oracle
    • Rushdi Shams, Dept of CSE, KUET Method Overriding- OracleMethod Overriding- Oracle
    • Rushdi Shams, Dept of CSE, KUET Method Overriding- OracleMethod Overriding- Oracle
    • Rushdi Shams, Dept of CSE, KUET Taking you to the RealityTaking you to the Reality 
    • Rushdi Shams, Dept of CSE, KUET Taking you to the RealityTaking you to the Reality   You can call the show() function for the supertypeYou can call the show() function for the supertype and subtypes in the table with the followingand subtypes in the table with the following
    • Rushdi Shams, Dept of CSE, KUET & The output& The output 
    • Rushdi Shams, Dept of CSE, KUET Method Overloading- TheoryMethod Overloading- Theory  Giving a type multiple methods with the sameGiving a type multiple methods with the same name is called method overloadingname is called method overloading
    • Rushdi Shams, Dept of CSE, KUET Method Overloading- OracleMethod Overloading- Oracle
    • Rushdi Shams, Dept of CSE, KUET Questions at the StageQuestions at the Stage  What are the difference between methodWhat are the difference between method overloading and method overriding?overloading and method overriding?  How Oracle implements method overriding?How Oracle implements method overriding?  How Oracle implements method overloading?How Oracle implements method overloading?
    • Rushdi Shams, Dept of CSE, KUET Map MethodsMap Methods  A map method is an optional kind of methodA map method is an optional kind of method  provides a basis for comparing objects byprovides a basis for comparing objects by mapping object instances to one of the scalarmapping object instances to one of the scalar types DATE, NUMBER, VARCHAR2 or to antypes DATE, NUMBER, VARCHAR2 or to an ANSI SQL type such as CHARACTER orANSI SQL type such as CHARACTER or REALREAL  With a map method, you can order any numberWith a map method, you can order any number of objects by calling each object's map methodof objects by calling each object's map method onceonce
    • Rushdi Shams, Dept of CSE, KUET Map MethodsMap Methods  a map method is simply a parameter-lessa map method is simply a parameter-less member functionmember function  uses the MAP keyworduses the MAP keyword  returns one of the datatypes just listedreturns one of the datatypes just listed  What makes a map method special is that, if anWhat makes a map method special is that, if an object type defines one, the method is calledobject type defines one, the method is called automatically to evaluate such comparisons asautomatically to evaluate such comparisons as obj_1 > obj_2obj_1 > obj_2
    • Rushdi Shams, Dept of CSE, KUET Map MethodMap Method  Where obj_1 and obj_2 are two object variablesWhere obj_1 and obj_2 are two object variables that can be compared using a map methodthat can be compared using a map method map(), the comparison:map(), the comparison: obj_1 > obj_2obj_1 > obj_2 is equivalent to:is equivalent to: obj_1.map() > obj_2.map()obj_1.map() > obj_2.map()
    • Rushdi Shams, Dept of CSE, KUET Map MethodMap Method
    • Rushdi Shams, Dept of CSE, KUET Order MethodOrder Method  Order methods make direct object-to-objectOrder methods make direct object-to-object comparisonscomparisons  Unlike map methods, they cannot map anyUnlike map methods, they cannot map any number of objectsnumber of objects  They simply tell you that the current object isThey simply tell you that the current object is less than, equal to, or greater than the otherless than, equal to, or greater than the other object that it is being compared to, with respectobject that it is being compared to, with respect to the criterion used by the methodto the criterion used by the method
    • Rushdi Shams, Dept of CSE, KUET Order MethodOrder Method
    • Rushdi Shams, Dept of CSE, KUET Question at the StageQuestion at the Stage  What are the methods used to compare OracleWhat are the methods used to compare Oracle objects? Can you give two examples to defineobjects? Can you give two examples to define them?them?  What are the differences between map methodWhat are the differences between map method and order method?and order method?
    • Rushdi Shams, Dept of CSE, KUET ReferenceReference  Oracle 10g User manual for Object OrientedOracle 10g User manual for Object Oriented Data ModelData Model  www.wikipedia.orgwww.wikipedia.org
    • Rushdi Shams, Dept of CSE, KUET AcknowledgementAcknowledgement  Nick Whittaker, Lecturer, University ofNick Whittaker, Lecturer, University of Manchester, UKManchester, UK