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Database management systems for managers : 

Database management systems for managers

Introduction : 

Introduction Efficient management of data Information age – Right decision at the right time. Acquire accurate, reliable and timely data about business and its operation. DBMS – A tool for analyzing and guiding the activities of business operations. Provides knowledge for competitive advantage. Essential for managing business, governments, banks, universities etc.

Basic Concepts and definitions : 

Basic Concepts and definitions Data Raw fact about something in which we are interested. Facts as numbers or text on a piece of paper, bits or bytes in computer’s memory, or facts stored in a person’s mind. Plural of datum which is single piece of information.

Basic Concepts and definitions : 

Basic Concepts and definitions Enterprise Data Model Operational Data Derived Data Reconciled Data Three-layer data structure

Basic Concepts and definitions : 

Information Processed, organized and summarized data. Involves the communication and reception of knowledge or intelligence. Warning signals before something starts going wrong. Predicts the future with reasonable level of accuracy and helps the organization in decision making. Basic Concepts and definitions

Basic Concepts and definitions : 

Basic Concepts and definitions Data warehousing Stores, retrieves, manages or manipulates massive amount of data being collected from organization’s database as well as from external sources. Different from traditional databases, is subject oriented rather than transaction oriented. Data from external sources is integrated with organizational database, supporting for decision making. ( integration of islands of data) Tools are used to mine the data like retrieving, analyzing and finding of patterns.

Basic Concepts and definitions : 

Basic Concepts and definitions Major components are : The data H/w are infrastructure for storing and accessing S/w for extracting data from external sources, converting into uniform format and storing in warehouse. Graphical query tool for mining A user guide for warehousing content Warehouse management software for IS personnel for maintenance and upgrading.

Basic Concepts and definitions : 

Metadata ( system catalog ) A data dictionary or data repository consists of metadata. Data that describes the data stored in the databases. List of the all tables, columns, domains, and assumptions. CASE tools are used for software design which has the ability to create, store , and search a comprehensive data dictionary. Basic Concepts and definitions

Basic Concepts and definitions : 

Basic Concepts and definitions Enterprise Data Model Operational Data Derived Data Reconciled Data Metadata layer Operational Meta data EDW Meta data Data mart Meta data Data layer Metadata layer

Basic Concepts and definitions : 

File concept Paper-based, manual filing systems are organized into Characters Data elements Records Files In a computer- based system data are organized in the following form Bit Byte Data element Records File Primary key Basic Concepts and definitions

Basic Concepts and definitions : 

File structures Sequential File structures Direct File structure Indexed Sequential File structure Sequential File structures Ordered by primary key Sequential access Difficult to get the details of a particular set of employees. Fast and inexpensive for batch processing operations. Ex : Payroll system. Direct File System Data is stored randomly. Requires special storage medium like optical disk, magnetic disk, or floppy disk. Basic Concepts and definitions

Basic Concepts and definitions : 

Specify a disk address for the records using hashing algorithm. Disadvantage is several record numbers may generate same address. Special processing can solve this problem but slow downs the storage and retrieval of records. Indexed Sequential File structure Records are stored sequentially on a direct access medium such as hard disk. A specific address for each record or block of records. Index is maintained. Known as indexed sequential access method (ISAM). Allows both sequential and random access. Requires maintenance of indexes. Basic Concepts and definitions

Basic Concepts and definitions : 

File types Master file Transaction file Report file ( extracting of relevant or desired data items in a record to prepare report) System catalog Is a system created database that describes all the database objects, data table creators, column names, data types, data size foreign keys and the primary key, indexed files, authorized users, user access privileges. Basic Concepts and definitions

Basic Concepts and definitions : 

System catalog is stored in system files which can be queried in the same manner as any other data table. Data item or fields Is the smallest unit of the data that has meaning to the user. Represented in the database by a value. Ex : Names, telephone numbers, bill amount etc. Molecules of the database. Bits and bytes are the atomic or sub-atomic elements which do not convey any meaning. Basic Concepts and definitions

Basic Concepts and definitions : 

Records Is a collection of logically related fields or data items. It is an occurrence of a named collection of zero, one or more than one data items. Files Is a collection of related sequence of records. All the records in file are of the same type or format. If every record in the file has exactly the same size, the file is said to be made up of fixed-length records. Otherwise the file is said to be of variable-length record. Basic Concepts and definitions