Aveek Gupta, CISA. IPCC Paper 7A: Information Technology Chapter 2

Transcription

1 Aveek Gupta, CISA IPCC Paper 7A: Information Technology Chapter 2

2 * DBMS/RDBMS 1 Administration Models DML and DDL Data Dictionaries Distributed DataBases Object Oriented DataBases Client Server DataBases Knowledge DataBases

3 A DBMS is a data storage and retrieval system which permits data to be stored non-redundantly. The physical location of data is not a concern of the user.

4 A RDBMS is a data storage and retrieval system where data is stored in tables that are associated by shared attributes (keys) and any data element (or entity) can be found in the database through the name of the table, the attribute name, and the value of the primary key.

5 Data Independence/Reduced Maintenance Improved Data Sharing Increased Application Development Productivity Enforcement of Standards Improved Data Quality (Constraints) Better Data Accessibility/ Responsiveness Advantages Security, Backup/Recovery, Concurrency

6 New, Specialized Personnel required Installation Management Cost and Complexity Conversion Costs Need for Explicit Backup and Recovery Costs & Risks Organizational Conflict

7 Entity: Object, Concept or event (subject) Database: a collection of tables Attribute: a Characteristic of an entity Table: a collection of records Row or Record: the specific characteristics of one entity

8 Each attribute has a unique name within an entity Each position (tuple) is limited to a single entry. All entries in the column are examples of it Ordering of rows and columns is unimportant Each row is unique

9 A data model is a representation of reality. It s used to define the storage and manipulation of a data base. Data Models have two components: Structure: the structure of the data stored within Operations: Facilities for manipulation of the data.

10 Create Operations occur at all levels: Delete Read Tables, Records, Columns Update

11 Ownership Depends on Regulation Depends on Parentage Assignment

12 PRIMARY KEY FOREIGN KEY Keys are used to form a RELATIONAL JOIN - thereby connecting row to row across the individual tables. PRIMARY KEY Serves as the row level addressing mechanism in the relational database model. It can be formed through the combination of several items. FOREIGN KEY A column or set of columns within a table that are required to match those of a primary key of a second table.

13 Cardinality Optionality Cardinality: oneto-one, one-tomany, many-tomany relationships Optionality: the relationship is either mandatory or optional.

14 Database integrity involves the maintenance of the logical and business rules of the database. Entity integrity deals with within-entity rules. Eg : Data-Type Integrity Referential integrity concerns two or more tables that are related.

15 DBA is a resource that supervises both the database and the use of the DBMS. DBA is usually a group, but sometimes it refers to the Database Administrator.

16 Policy Formulation and Implementation Database design Data Dictionary Management DBMS Support Training

17 Access Privileges Users should access the database only in ways in which they are entitled. Security Access restrictions ensure that the database is secure. Passwords, encryption, and views implement security. Effective password protection is critical. Database design DBMS Support Policy Formulation and Implementation Training Data Dictionary Management

18 Database design DBMS Support Policy Formulation and Implementation Training Data Dictionary Management Essentially the catalog, but it contains a wider range of information, including information on tables, fields, indexes, and programs. The DBA manages and updates the data dictionary, which establishes naming conventions for tables, fields, etc., and data integrity rules.

19 Database design Policy Formulation and Implementation Data Dictionary Management Training DBA gives training on the DBMS and how to access the database DBMS Support Training

20 Database design DBMS Support Policy Formulation and Implementation Training Data Dictionary Management DBMS Support The DBA is entrusted(charged) with all aspects of a DBMS, including selection and management DBA must evaluate each prospective DBMS using a checklist

21 Database design DBMS Support Policy Formulation and Implementation Training Data Dictionary Management DBA is responsible for tuning the design, i.e., making changes that improve system performance.

22 Entity-relationship (ER) diagrams A data model that uses basic graphical symbols to show the organization of and relationships between data

23 Last name Attributes Entities Colour First name Customer 1 N Order Product Name 1:N one-to-many relationship Identification number Identification number

24 Subschema A DBMS Schema Subschema B Schema A description of the entire database Subschema A file that contains a description of a subset of the database and identifies which users can perform modifications on the data items in that subset User 1 User 2 User 3 In a Relational database, the schema defines the tables, the fields in each table, and the relationships between fields and tables.

25 Data Definition Language ( DDL) CREATE Concurrency Control Data Modification language (DML) DELETE

26 Concurrency Control Data Definition Language ( DDL) Data Modification language (DML) Data Definition Language (DDL) A collection of instructions and commands used to define and describe data and data relationships in a specific database Eg : CREATE command

27 Concurrency Control Data Definition Language ( DDL) Data Modification language (DML) Data Manipulation Language (DML) The commands that are used to manipulate the data in a database. Structured query language (SQL) is an example of a standardised Data Manipulation Language Eg : INSERT/UPDATE commands

28 Concurrency Control Data Definition Language ( DDL) Data Modification language (DML) Concurrency Control A method of dealing with a situation in which two or more people need to access the same record in a database at the same time

29 Concurrency Control Data Definition Language ( DDL) Data Modification language (DML) SELECT.. ( *) FROM. (Employees(Table)) WHERE. (Name = RAM ) (gets all information of employee named RAM from the Employees table) the SELECT clause specifies the columns of the result the FROM clause specifies the tables to be scanned in the query the WHERE clause specifies the condition on the columns of the tables in the FROM clause wildcard searches use: % : matches any substring _ : matches any character

30 Easier modification of data and information Provide a standard definition of terms and data elements Features Assist programmers in designing and writing programs Data Dictionary A detailed description of all data used in the database Increase data reliability Simplify database modification Reduce data redundancy

31 A database in which the actual data may be spread across several smaller databases connected via telecommunication devices

32 It is based on the concept that anything can be modeled in terms of Objects and their interactions. It maintains a direct correspondence between realworld and database objects

33 A database containing both Declarative data and Procedural data makes up Knowledge database

34 Declarative data describes the STATIC part of real world objects and their associations.

35 Procedural data refers to the DYNAMIC part of real world objects and their associations. A knowledge database is more voluminous and can help the management in taking better decisions.

36 A query language is a set of commands to create, update and access data from a database allowing users to raise ad-hoc queries/questions interactively without the help of programmers. It is a computer programming language used to manipulate information in relational database management systems (RDBMS).

37 Data Definition Language (DDL) : It defines the conceptual schema providing a link between the logical and physical structures of the database. The logical structure of a database is a schema. A subschema is the way a specific application views the data from the database. Following are the functions of Data Definition Language (DDL) : They define the physical characteristics of each record, field in the record, field s type and length, field s logical name and also specify relationships among the records.

38 They describe the schema and subschema. They indicate the keys of the record. They provide means for associating related records or fields. They provide for data security measures. They provide for logical and physical data independence.

39 Data Manipulation Language (DML) : DML is a Database Language used by data base users to retrieve, insert, delete and update data in a database. Following are the functions of Data Manipulation Language (DML) : They provide the data manipulation techniques like deletion, modification, insertion, replacement, retrieval, sorting and display of data or records.

40 Data Manipulation Language (DML) facilitate use of relationships between the records. They enable the user and application program to be independent of the physical data structures and database structures maintenance by allowing to process data on a logical and symbolic basis rather than on a physical location basis. They provide for independence of programming languages by supporting several high-level procedural languages like COBOL, C++ etc.