WHAT IS RDBMS?
- RDBMS stands for Relational Database Management System. RDBMS data is structured in database tables, fields and records.
- Each RDBMS table consists of database table rows. Each database table row consists of one or more database table fields.
- RDBMS store the data into collection of tables, which might be related by common fields (database table columns).
- RDBMS also provide relational operators to manipulate the data stored into the database tables. Most RDBMS use SQL as database querylanguage. The most popular RDBMS are MS SQL Server, DB2, Oracle and MySQL.
- The relational model is an example of record-based model.
- Record based models are so named because the database is structured in fixed format records of several types. Each table contains records of a particular type. Each record type defines a fixed number of fields, or attributes.
- The columns of the table correspond to the attributes of the record types. The relational data model is the most widely used data model, and a vast majority of current database systems are based on the relational model.
- Provides data to be stored in tables
- Persists data in the form of rows and columns
- Provides facility primary key, to uniquely identify the rows
- Creates indexes for quicker data retrieval
- Provides a virtual table creation in which sensitive data can be stored and simplified query can be applied.(views)
- Sharing a common column in two or more tables(primary key and foreign key)
- Provides multi user accessibility that can be controlled by individual users.Explain Product of RDBMS
Characteristic of RDBMS
- Data abstraction
- Self-describing data
- Support for multiple views
- The use of keys. Each row of data in a table is identified by a unique "key", called the primary key.
- Avoiding data redundancy.
- Constraining the input.
- Maintaining data integrity.
- Structured Query Language (SQL) .
How it works
- Data is represented in terms of tuples (rows) in RDBMS.
- Relational database is most commonly used database. It contains number of tables and each table has its own primary key.
- Due to a collection of organized set of tables, data can be accessed easily in RDBMS.
Advantages of RDBMS:
- ➨It is easy to use.
- ➨It is secured in nature.
- ➨The data manipulation can be done.
- ➨It limits redundancy and replication of the data.
- ➨It offers better data integrity.
- ➨It provides better physical data independence.
- ➨It offers logical database independence i.e. data can be viewed in different ways by the different users.
- ➨It provides better backup and recovery procedures.
- ➨It provides multiple interfaces.
- ➨Multiple users can access the database which is not possible in DBMS.
Disadvantages of RDBMS:
- ➨Software is expensive.
- ➨Complex software refers to expensive hardware and hence increases overall cost to avail the RDBMS service.
- ➨It requires skilled human resources to implement.
- ➨Certain applications are slow in processing.
- ➨It is difficult to recover the lost data.
The goal of a relational database design is to generate a set of relation schema that allows us to store information without unnecessary redundancy and also to retrieve information easily. A database system is an integrated collection of related files, along with details of interpretation of the data contained therein. DBMS is a s/w system that allows access to data contained in a database. The objective of the DBMS is to provide a convenient and effective method of defining, storing and retrieving the information contained in the database. The DBMS interfaces with application programs so that the data contained in the database can be used by multiple applications and users. The DBMS allows these users to access and manipulate the data contained in the database in a convenient and effective manner. In addition the DBMS exerts centralized control of the database, prevents unauthorized users from accessing the data and ensures privacy of data.