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Relational Database Management System (RDBMS)

Published in: DBMS & RDBMS | PL/SQL
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RDBMS basis introduction ppt.

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    Relational Database Management System RDBMS-INTRO-SRR 10/25/2018
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    Introduction Purpose of Database Systems View of Data Data Models Data Definition Language Data Manipulation Language Transaction Management Storage Management Database Administrator Database Users Overall System Structure RDBMS-INTRO-SRR 10/25/2018
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    Database Management System (DBMS) Collection of interrelated a a and a set of programs to access the data. DBMS contains information about a particular enterprise DBMS provides an environment that is both convenient and efficient to use. Database Applications: O O O O O O Banking: transactions Airlines: reservations, schedules Universities: registration, examination Sales: customers, products, purchases Manufacturing: production, inventory, orders, supply chain Human resources: employee records, salaries, tax deductions Databases touch all aspects of our lives RDBMS-INTRO-SRR 10/25/2018
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    Purpose of Database System In the early days, database applications were built on top of file systems Drawbacks of using file systems to store data: Data redundancy and inconsistency o Multiple file formats, duplication of information in different files Difficulty in accessing data o Need to write a new program to carry out each new task Data isolation — multiple files and formats o Integrity problems o Integrity constraints (e.g. account balance > o) become part of program code Hard to add new constraints or change existing ones RDBMS-INTRO-SRR 10/25/2018
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    Purpose o Data ase Systems Drawbacks of using file systems (cont.) Atomicity of updates o Cont, Failures may leave database in an inconsistent state with partial updates carried out E.g. transfer of funds from one account to another should either complete or not happen at all Concurrent access by multiple users O Concurrent accessed needed for performance Uncontrolled concurrent accesses can lead to inconsistencies o E.g. two people reading a balance and updating it at the same time Security problems o o Database systems offer solutions to all the above problems RDBMS-INTRO-SRR 10/25/2018
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    Levels of Abstraction Physical level describes how data/a record (e.g., customer) is stored, Logical level: describes what data are stored in database, and the relationships among the data. View level: describes what data be accessible to a specific application/ user. RDBMS-INTRO-SRR 10/25/2018
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    View of Data An architecture for a database system vievv level logical level physical level RDBMS-INTRO-SRR 10/25/2018
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    Instances and Schemas Schema — the logical structure of the database Physical schema: database design at the physical level Logical schema: database design at the logical level O Instance — the actual content of the database at a particular point in time Data Independence: The ability to modify the schema at a level without requiring to modify the next higher level of abstraction Physical Data Independence — the ability to modify the physical schema without changing the logical schema Logical Data Independence — the ability to modify the logical schema without changing the view schema Applications depend on the logical schema o In general, the interfaces between the various levels and components should be well o defined so that changes in some parts do not seriously influence others. RDBMS-INTRO-SRR 10/25/2018
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    Data Models A collection of tools for describing data data relationships data semantics data constraints Entity-Relationship model o Relational model O Other models o Object-Oriented model Object- Relational data models Older models: network model and hierarchical model RDBMS-INTRO-SRR 10/25/2018
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    Entity-Relationship Model 10 Example of schema in the entity-relationship model customer-name customer-id customer-street customer-city account-number balance customer RDBMS-INTRO-SRR depositor account 10/25/2018
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    Entity Relationship Model (Cont,) 11 E-R model of real world Entities (objects) o E.g. customers, accounts, bank branch Relationships between entities o E.g. Account A-101 is held by customer Johnson Relationship set depositor associates customers with accounts Widely used for database design E-R model is usually converted to the relational model, which O is used for storage and processing RDBMS-INTRO-SRR 10/25/2018
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    Relational Model Customer-id 192-83-7465 019-28-3746 192-83-7465 321-12-3123 019-28-3746 customer- name Johnson Smith Johnson Jones Smith 12 customer- street Alma North Alma Main North customer- city Palo Alto Rye Palo Alto Harrison Rye Attributes account- number A-101 A-215 A-201 A-217 A-201 Example of tabular data in the relational model RDBMS-INTRO-SRR 10/25/2018
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    A Sample Relational Database customer Id customer •name 192-83-7465 019-28-3746 677-89-9011 182-73-6091 321-12-3123 336-66—9999 019-28-3746 account-number A-101 A-215 A-102 A-305 A-201 A-217 A-222 Johnson Srnith Hayes Turner Jones Lindsay Srnith customer-street 12 Alnaa St. 4 North St. 3 Main St. 123 Putnarn Ave. 100 Main St. 175 Park Ave. 72 North St. customer-city Palo Alto Rye Harrison Stanford Harrison Pittsfield Rye (a) The customer table balance 500 700 350 900 750 700 customer-id 192-83-7465 192-83-7465 019-28-3746 677-89-9011 182-73-6091 321-12-3123 336-66 _9999 019-28-3746 account-number A-101 A-201 A-215 A-102 A-305 A-217 A-222 A-201 (b) The account table RDBMS-INTRO-SRR (c) The depositor table 10/25/2018
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    Data Definition Language (DDL) Used for specification of the database schema E.g. create table account ( account-number char(10), balance integer) DDL compiler generates a set of tables stored in a data dictionary Data dictionary contains metadata (i.e., data about data) database schema o Data storage and definition language O language in which the storage structure and access methods used by the database system are specified Usually an extension of the data definition language RDBMS-INTRO-SRR 10/25/2018
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    Data Manipulation Language (DML) 15 Language for accessing and manipulating the data, organized by the appropriate data model DML is also known as query language o Two classes of languages Procedural — user specifies what data is required and how to O get those data Nonprocedural — user specifies what data is required without o specifying how to get those data SQL is the most widely used query language RDBMS-INTRO-SRR 10/25/2018
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    SQL 16 widely used non-proce ural language SQL: E.g. find the name of the customer with customer-id 192-83-7465 o select customer.customer-name from customer where customer.customer-id = '192-83-7465' E.g. find the balances of all accounts held by the customer with O customer-id 192-83-7465 select account.balance from depositor, account where depositor.customer-id = '192-83-7465' and depositor.account-number = account.account-number Application programs generally access databases through one of Language extensions to allow embedded SQL Application program interface (e.g. ODBC/JDBC) which allow SQL O queries to be sent to a database RDBMS-INTRO-SRR 10/25/2018
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    Database Users Users are differentiated by the way they expect to interact with the system Application programmers — interact with system through DML calls Specialized users — write specialized database applications that do not fit into the traditional data processing framework Naive users — invoke one of the permanent application programs that have been written previously E.g. people accessing database over the web, bank tellers, clerical O staff RDBMS-INTRO-SRR 10/25/2018
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    Database Administrator 18 Coordinates all the activities of the database system; the database administrator has a good understanding of the enterprise's information resources and needs. Database administrator's duties include: O O O O O O O Schema definition Storage structure and access method definition Schema and physical organization modification Granting user authority to access the database Specifying integrity constraints Acting as liaison with users Monitoring performance and responding to changes in requirements RDBMS-INTRO-SRR 10/25/2018
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    Transaction Management 19 A transaction is a collection of operations that performs a single logical function in a database application Transaction-management component ensures that the database remains in a consistent (correct) state despite system failures (e.g., power failures and operating system crashes) and transaction failures. Concurrency-control manager controls the interaction among the concurrent transactions, to ensure the consistency of the database. RDBMS-INTRO-SRR 10/25/2018
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    Storage Management 20 Storage manager is a program module that provides an interface between the low-level data stored in the database and the application programs and queries submitted to the system. The storage manager is responsible to the following tasks: o interaction with the file manager efficient storing, retrieving and updating of data O RDBMS-INTRO-SRR 10/25/2018
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    Overall System Structure ica Ei p r ers p iler a-rud file 21 LÄN•IL queries p p Li tic•xx tox- L irtterpretex- trails disk irtc±i. ces d icti•01Tary statistical data RDBMS-INTRO-SRR 10/25/2018
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    Application Architectures user application network database system a. two-tier architecture 22 client server user application client network application server database system b. three-tier architecture •Two-tier architecture: E.g. client programs using ODBC/JDBC to communicate with a database •Three-tier architecture: E.g. web-based applications, and applications built using "middleware" RDBMS-INTRO-SRR 10/25/2018
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    History 23 1950s and early 1960s: Data processing using magnetic tapes for storage O Tapes provide only sequential access Punched cards for input O Late 1960s and 1970s: Hard disks allow direct access to data O Network and hierarchical data models in widespread use O Ted Codd defines the relational data model O Would win the ACM Turing Award for this work IBM Research begins System R prototype UC Berkeley begins Ingres prototype High-performance (for the era) transaction processing O RDBMS-INTRO-SRR 10/25/2018
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    History 24 1980s: Research relational prototypes evolve into commercial systems O SQL becomes industrial standard Parallel and distributed database systems O Object-oriented database systems O 1990s: Large decision support and data-mining applications O Large multi-terabyte data warehouses O Emergence of Web commerce O 2000s: XML and XQuery standards O Automated database administration O RDBMS-INTRO-SRR 10/25/2018
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    RDBMS-INTRO-SRR Thank you 25 10/25/2018


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