The database is an organized collection of structured data to make it easily accessible, manageable and update. In simple words, you can say, a database in a place where the data is stored. The best analogy is the library. The library contains a huge collection of books of different genres, here the library is database and books are the data.
In layman terms, consider your school registry. All the details of the students are entered in a single file. You get the details regarding the students in this file. This is called a Database where you can access the information of any student.
Facts about Database:
- Databases have evolved dramatically since their inception in the early 1960s.
- Some Navigational databases such as the Hierarchical database and the Network database were the original systems used to store and manipulate data. Although these early systems were actually inflexible
- In the early 1980s, Relational databases became very popular, which was followed by object-oriented databases later on.
- More recently, NoSQL databases came up as a response to the growth of the internet and the need for faster speed and processing of unstructured data.
- Today, we have cloud databases and self-driving databases that are creating a new ground when it comes to how data is collected, stored, managed, and utilized.
The major components of the Database are:
This consists of a set of physical electronic devices such as I/O devices, storage devices and many more. It also provides an interface between computers and real-world systems.
This is the set of programs that are used to control and manage the overall Database. It also includes the DBMS software itself. The Operating System, the network software being used to share the data among the users, the application programs used to access data in the DBMS.
Database Management System collects, stores, processes, and accesses data. The Database holds both the actual or operational data and the metadata.
These are the rules and instructions on how to use the Database in order to design and run the DBMS, to guide the users that operate and manage it.
- Database Access Language
It is used to access the data to and from the database. In order to enter new data, updating, or retrieving requires data from databases. You can write a set of appropriate commands in the database access language, submit these to the DBMS, which then processes the data and generates it, displays a set of results into a user-readable form.
Advantage of database
- Reduced data redundancy.
- Also, there is reduced updating errors and increased consistency.
- Easier data integrity from application programs.
- Improved data access to users through the use of host and query languages.
- Data security is also improved.
- Reduced data entry, storage, and retrieval costs.
Disadvantage of database
- Complexity: Databases are complex hardware and software systems.
- Cost: It requires significant upfront and ongoing financial resources.
- Security: Most leading companies need to know that their Database systems can securely store data, including sensitive employee and customer information.
- Compatibility: There is a risk that a DBMS might not be compatible with a company’s operational requirements.
Types of Database
There are a few types that are very important and popular.
- Relational Database
- Object-Oriented Database
- Distributed Database
- NoSQL Database
- Graph Database
- Cloud Database
- Centralization Database
- Operational Database
Purpose of Database
A database should be a repository of data needed for an organization’s data processing. That data should be accurate, private, and protected from damage. It should be accurate so that diverse applications with different data requirements can employ the data. Different application programmers and various end-users have different views upon data, which must be derived from a common overall data structure. Their methods of searching and accessing of data will be different.
Various Levels of Database Implementation
The database is implemented through three general levels. These levels are:
- Internal Level or Physical level
- Conceptual Level
- External Level or View Level
The Concept of Data Independence
As the database may be viewed through three levels of abstraction, any change at any level can affect other levels’ schemas. Since the database keeps on growing, then there may be frequent changes at times. This should not lead to redesigning and re-implementation of the database. The concepts of data independence prove beneficial in such types of contexts.
- Physical data independence
- Logical data independence
Basic Terminologies Related to Database and SQL
In general, a relation is a table, i.e., data is arranged in rows and columns. A relation has the following properties:
- In any given column of a table, all the items are of the same kind, whereas items in different columns may not be of the same kind.
- For a row, each column must have an atomic value, and also for a row, a column cannot have more than one value.
- All rows of a relation are distinct.
- The ordering of rows in a relationship is immaterial.
- The column of a relation are assigned distinct names, and the ordering of these columns is immaterial.
The rows of tables in a relationship are generally termed as Tuples.
The columns or fields of a table is termed as Attributes.
The number of attributes in a relation determines the degree of relation. A relation having three attributes is said to have a relation of degree 3.
(v) Cardinality: The number of tuples or rows in a relation is termed as cardinality.