¾ Data warehouse is subject Oriented, Integrated, Time-Variant and nonvolatile collection of data that support of management’s decision making process.
- Subject Oriented – The Data warehouse is subject oriented because it provides us the information around a subject rather the organization’s ongoing operations. These subjects can be product, customers, suppliers, sales, revenue etc. The data warehouse does not focus on the ongoing operations rather it focuses on modeling and analysis of data for decision making.
- Integrated – Data Warehouse is constructed by integration of data from heterogeneous sources such as relational databases, flat files etc. This integration enhances the effective analysis of data.
- Time-Variant – The Data in Data Warehouse is identified with a particular time period. The data in data warehouse provide information from historical point of view.
- Non Volatile – Non volatile means that the previous data is not removed when new data is added to it. The data warehouse is kept separate from the operational database therefore frequent changes in operational database is not reflected in data warehouse.
- Metadata – Metadata is simply defined as data about data. The data that are used to represent other data is known as metadata. For example the index of a book serve as metadata for the contents in the book
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DATA WAREHOUSE TOOLS AND UTILITIES FUNCTIONS
The following are the functions of Data Warehouse tools and Utilities:
- Data Extraction – Data Extraction involves gathering the data from multiple heterogeneous sources.
- Data Cleaning – Data Cleaning involves finding and correcting the errors in data.
- Data Transformation – Data Transformation involves converting data from legacy format to warehouse format.
- Data Loading – Data loading involves sorting, summarizing, consolidating, checking integrity and building indices and partitions.
- Refreshing – Refreshing involves updating from data sources to warehouse.
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public static void main(String args)
String original, reverse=””;
Scanner in = new Scanner(System.in);
System.out.println(“Enter a string to check if it is a palindrome”);
original = in.nextLine();
int length = original.length();
for ( int i = length – 1 ; i >= 0 ; i– )
reverse = reverse + original.charAt(i);
System.out.println(“Entered string is a palindrome.”);
System.out.println(“Entered string is not a palindrome.”);
Components of the Database System Environment
There are five major components in the database system environment and their interrelationship are –
1. Hardware: The hardware is the actual computer system used for keeping and accessing the database.
2. Software: The software is the actual DBMS. Between the physical databases itself (i.e. the data as actually stored) and the users of the system is a layer of software, usually called the Database Management System or DBMS. All requests from users for access to the database are handled by the DBMS. One general function provided by the DBMS is thus the shielding of database users from complex hardware-level detail.
3. Data: It is the most important component of DBMS environment from the end users point of view. As shown in figure that data acts as a bridge between the machine components and the user components. The database contains the operational data and the meta-data, the ‘data about data’.
4. Users: There are a number of users who can access or retrieve data on demand using the applications and interfaces provided by the DBMS. Each type of user needs different software capabilities. The users of a database system can be classified in the following groups, depending on their degrees of expertise or the mode of their interactions with the DBMS. The users can be:
• Naive Users
• Online Users
• Application Programmers
• Sophisticated Users
• Data Base Administrator (DBA)
5. Procedures: Procedures refer to the instructions and rules that govern the design and use of the database. The users of the system and the staff that manage the database require documented procedures on how to use or run the system.
These may consist of instructions on how to:
• Log on to the DBMS.
• Use a particular DBMS facility or application program.
• Start and stop the DBMS.
• Make backup copies of the database.
• Handle hardware or software failures.
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WHAT IS DATABASE MANAGEMENT SYSTEM?
The Database Management System is to provide a convenient and efficient way to store and retrieve data stored in a database.
A database is a computer generated software program which can be used to access the data stored in database in an organized manner.
The term database is a structured collection of data stored which can be stored in digital form. Before the actual data is stored in the database, we should clearly specify the schema of the database and different techniques used to manipulate the data stored in a database.
DBMS must provide efficient techniques in order to protect the data from accidental system crashes.
WHERE IS DATABASE MANAGEMENT SYSTEM USED?
DBMS systems can be used extensively in the following fields –
1. Transportation: DBMS system can be used for reservation or cancellation of tickets and can be also used to check for the schedules of incoming and outgoing flights.
2. Education: DBMS system can be used by different universities to allow students take admission online, checking the status of vacant seats, enrolment system can be done computerized etc.
3. Banking: DBMS system has completely changed the face of the banking sector. Few decades ago, the banking system was purely the paper based system have now transformed in keeping less of paper work.
4. Sales: DBMS system allows the data to be stored in electronic format by making use of relational databases which allows the data to be stored in highly organized manner. This database allows the information such as information about the customers, products, sales, purchases etc to be stored in database.
5. Manufacturing: DBMS system allows the user to store information about the production of good, the inventory details, the total number of orders, supply chain information in database so that it allows the decision makers to make critical decisions in timely manner.
6. Human Resource: DBMS has made the life of HR team much better by allowing the team to compute tax deductions, employee wages, retrieving the details of the employees in faster manner as compared to traditional paper based approach which was time consuming.
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WHAT IS DATABASE?
Database is collection of data which is related by some aspect. Data is collection of facts and figures which can be processed to produce information. Name of a student, age, class and her subjects can be counted as data for recording purposes.
WHAT ARE THE FEATURES OF DBMS?
Real-world entity: Modern DBMS are more realistic and uses real world entities to design its architecture. It uses the behavior and attributes too. For example, a school database may use student as entity and their age as their attribute.
Relation-based tables: DBMS allows entities and relations among them to form as tables. This eases the concept of data saving. A user can understand the architecture of database just by looking at table names etc.
Isolation of data and application: A database system is entirely different than its data. DBMS stores metadata which is data about data, to ease its own process.
Less redundancy: DBMS follows rules of normalization, which splits a relation when any of its attributes is having redundancy in values. Following normalization, which itself is a mathematically rich and scientific process, make the entire database to contain as less redundancy as possible.
Consistency: DBMS always enjoy the state on consistency where the previous form of data storing applications like file processing does not guarantee this. Consistency is a state where every relation in database remains consistent.
Query Language: DBMS is equipped with query language, which makes it more efficient to retrieve and manipulate data. A user can apply as many and different filtering options, as he or she wants. Traditionally it was not possible where file-processing system was used.
ACID Properties: DBMS follows the concepts for ACID properties, which stands for Atomicity, Consistency, Isolation and Durability. These concepts are applied on transactions, which manipulate data in database.
Multiuser and Concurrent Access: DBMS support multi-user environment and allows them to access and manipulate data in parallel. Though there are restrictions on transactions when they attempt to handle same data item, but users are always unaware of them.
Multiple views: DBMS offers multiples views for different users. A user who is in sales department will have a different view of database than a person working in production department. This enables user to have a concentrate view of database according to their requirements.
Security: Features like multiple views offers security at some extent where users are unable to access data of other users and departments.
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