Introduction to Databases
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The document introduces databases and relational database management systems (RDBMS). It defines a database as both the storage location for data and the method for structuring and organizing data, such as using tables. Benefits of databases are listed as efficient data access, security, and recoverability. The document provides an overview of RDBMS, including an example of related tables to store employee and department data. Key concepts of RDBMS are described as relational structures between tables, data normalization, and using constraints.
Introduction to Databases
- 2. Copyright 2014 © Ram Kedem. All rights reserved. Not to be reproduced without written consent Objectives • Defining Database • Why do we need Database ? • RDBMS High Overview • RDBMS Main Charachterisitcs
- 3. Copyright 2014 © Ram Kedem. All rights reserved. Not to be reproduced without written consent Defining Database • What is a Database • The actual server on which our data resides • A method we use in order to save all our data • Flat File (text file) • Hierarchical Method • Using Tables • And many more ..
- 4. Copyright 2014 © Ram Kedem. All rights reserved. Not to be reproduced without written consent Defining Database (1) Database as a storage • A storage by which our data is being kept, also refered as the machine that runs our database program.
- 5. Copyright 2014 © Ram Kedem. All rights reserved. Not to be reproduced without written consent Defining Database (2) Database as a method • Formally, a "database" refers to a set of related data and the way it is structured or organized, a method we use in order to store our data. • Unstructured data (for example flat file)
- 6. Copyright 2014 © Ram Kedem. All rights reserved. Not to be reproduced without written consent • A method we use in order to store our data • Hierarchical data Defining Database (2) Database as a method
- 7. Copyright 2014 © Ram Kedem. All rights reserved. Not to be reproduced without written consent • A method we use in order to store our data • Structured data – using tables • SQL language was developed in order to allow us retrieve data from these structures (tables) • This method is also refered as RDBMS – the Relational Database Management System Defining Database (2) Database as a method
- 8. Copyright 2014 © Ram Kedem. All rights reserved. Not to be reproduced without written consent Database Benefits • Aside from storing our data and providing us a method to keep it, databases have many more benefits : • Efficient reads • Efficient writes • Enhanced security • Recoverability • And many more ..
- 9. Copyright 2014 © Ram Kedem. All rights reserved. Not to be reproduced without written consent RDBMS High Overview • Relational Database management system • Table structures Employee id First Name Last Name Department Id 100 Steven Spielberg 50 101 Quentin Tarantino 60 Department Name Sales IT Department Id Department Name 50 Sales 60 IT Employees Table Departments Table
- 10. Copyright 2014 © Ram Kedem. All rights reserved. Not to be reproduced without written consent RDBMS High Overview • Relational Database management system • Table structures Employee id First Name Last Name Department Id 100 Steven Spielberg 50 101 Quentin Tarantino 60 Department Id Department Name 50 Sales 60 IT Employees Table Departments Table
- 11. Copyright 2014 © Ram Kedem. All rights reserved. Not to be reproduced without written consent RDBMS Main Concepts • Relational Structure – each table can be related to another based on common column. • Normalization - the process of organizing the attributes and tables of a relational database to minimize data redundancy. Basicaly each column should appear only once (normalized state). • Constraints – rules we can enforce on specific column.
- 12. Copyright 2014 © Ram Kedem. All rights reserved. Not to be reproduced without written consent Essential Points • The term Database can refer to the actual machine on which we are saving the data. It may also refer the method we use to store the data. • Other than just keeping our data, databases provide many benefits (efficient reads / writes, enchanced security, etc.) • In RDBMS our data is stored in tables, each table can be related to another. In most cases data should be normalized. We can also use constraints to better enforce our data integritiy.