Key Points:

1. Data is a raw facts and figures, which is isolated, un-interpreted and unorganized but able to organize into useful information. It is a set of values of subjects with respect to qualitative or quantitative variables.
2. Information is the processed or organized form of date i.e., after processing the data we can get information. When data are processed using a database program or software, data are converted into meaningful result called information.
3. Database is a collection of related data about a topic or subject organized in a useful manner that provides a base or foundation for the procedure, such as retrieving information, drawing a conclusion and make a decision.
4. Database management system (DBMS) is a collection of programs that enables users to create, operate and maintain a database.  It is a set of program or software to manage, handle database files and allows to access, update data as requested.
5. The advantages of DBMS are:
   1. data can be shared,
   2. reduce data redundancy,
   3. integrity can be maintained,
   4. data independence,
   5. data availability,
   6. standard can be enforced,
   7. security can be improved,
   8. inconsistency can be avoided,
   9. providing multiple user interfaces,
   10. providing options for backup and recovery. 
6. RDBMS (Relational DBMS): is a collection of programs and capabilities that enable IT teams and users to create, update, administer and otherwise interact with a relational database. It is a software used for creating, operating and maintaining a relational database.  E.g. SQL, Mariadb, MySQL, Oracle etc. DBMS allows users the following tasks:

Data definition, Data Update, Data Retrieval, User Administration.

• Key is a field that uniquely identifies the records, tables or data. In the relational data model, there are many keys.
• Primary key is one or more column(s) in a table used to uniquely identify each row in the table. It is a candidate key chosen by a database designer to uniquely identify the entity from entity set.
• A foreign key is a column whose values are derived from the primary key of some other table.
• Unique key is one or more column(s) in a table used to uniquely identify each row in the table.
• A super key is a set of one or more attributes that taken collectively, allow us to identify uniquely a tuple in the relation.
• Composite Key: is a primary key composed of multiple columns used to identify a record uniquely.
• Database system: provides a data-definition language to specify the database schema and a data manipulation language to express database queries and updates.
• SQL (Structured Query Language) is a database language used for defining and manipulating database. 
• DDL (Data Definition Language) is used by the database designers and programmers to specify the content and structure of the database. It allows a database administrator to define the database structure, schema and subschema. 
• DML (Data Manipulation Language) provides the techniques for processing the database, such as retrieval, sorting, display and deletion of data or record.  It allows an end user to manipulate the data in the database.
• Data dictionary is a file or a set of files that contains a database’s metadata (data about database). The data dictionary contains records about other objects in the database, such as data ownership, data relationships to other objects, and other data. It is a crucial component of any relational database. 
• Database model describes the structure of a database.  Different database models are hierarchical model, network model, and relational model. 
• Five different types of Database model:

Hierarchical model, Network model, Relational model, Entity-relationship model and Object-oriented model.

• E – R diagram is a graphical representation of different entities and their relationship.  It is a graphical representation of the database. 
• An entity is a ‘thing’ or ‘person’ or ‘object’ in the real world that is distinguishable from all other objects. 
• An attribute is the characteristics of the entity. 
• A relationship is the association between two entities.  It can be one – to – one, one – to – many, many to one or many to many. 
• Normalization is a process for evaluating and correcting table structures to minimize data redundancies, thereby reducing the likelihood of data anomalies. It is the process of breaking down the complex table or relation into multiple smaller tables to avoid undesirable things such as repetition of information, inability to represent information, loss of information etc. 
• Different normal forms are: First Normal Form (1NF), Second Normal Form (2NF), Third Normal Form (3NF), Boyce Codd Normal Form (BCNF), Fourth Normal Form (4NF).
• A relation or table is said to be in 1NF if it’s all attributes or each attribute of the relation are atomic. 
• A relation is said to be in second normal form (2NF) if it is in first normal form and each attribute is functionally dependent on the entire primary key. 
• A relation is said to be in third normal form (3NF) if itis in second normal form and it does not contain any transitive dependency on the primary key. 
• In a centralized database, data resides in a single central location. 
• In distributed database, data resides in multiple servers distributed in different location but connected with each other. 
• Data security refers to the protection of data against unauthorized access and the accidental issues. 
• Data abstraction refers to the process of providing users with an abstract view of the data by hiding certain details of how the data are stored and maintained. 
• DBA (Database Administrator) is person responsible for designing, developing, controlling and looking after the database. 
• Data integrity or integrity constraint is a rule that restricts the values ​​that may be present in the database.  It ensures that changes made to the database by authorized users do not result in a loss of data consistency.  Different types of data integrity are: entity integrity, referential integrity and domain integrity.
• Record is a collection of logically related fields or data items, with each field processing fixed number of bytes and having a fixed data type.
• A file is a collection of related sequence of records.
•  The system stores permanent records in various files and add record to appropriate files.
• A centralized database has one central computer called database server, to store all the data and files and it provides services to all the clients in the networks.
• Distributed database system is a set of databases stored on multiple computers that appears to applications as a single database.