Keys are used in RDBMS. Transaction management Inefficient, Error prone and insecure. Efficient and secure. Distributed Databases Not supported Supported by RDBMS.
Example Dbase, FoxPro. SQL server, Oracle, mysql, MariaDB, SQLite, MS Access. Database normalization was first proposed by Dr. Edgar F Codd as an integral part of RDBMS in order to reduce data redundancy and improve data integrity.
These rules are known as E F Codd Rules. 12th Computer Chapter - - Types of Relationships . Following are the types of relationships used in a database. .
One-to-One Relationship . One-to-Many Relationship . Many-to-One Relationship . Many-to-Many Relationship .
One-to-One Relationship In One-to-One Relationship, one entity is related with only one other entity. One row in a table is linked with only one row in another table and vice versa. For example: A student can have only one exam number One to one Relationships Fig . Student Exam No Jayapandiyan Tamilselvi Sarojini .
One-to-Many Relationship In One-to-Many relationship, one entity is related to many other entities. One row in a table A is linked to many rows in a table B, but one row in a table B is linked to only one row in table A. For example: One Department has many staff members. One to Many Mapping Fig .
Department Staff Computer Tamil Maths Gajalakshmi Bindhu Radha Ramesh Malaiarasu . Many-to-One Relationship In Many-to-One Relationship, many entities can be related with only one in the other entity. For example: A number of staff members working in one Department. Multiple rows in staff members table is related with only one row in Department table.
Many to one Relationship Fig . Staff Department Computer Maths Suganya Bala Valarmathi 12th Computer Chapter - - Database Concepts . Many-to-Many Relationship A many-to-many relationship occurs when multiple records in a table are associated with multiple records in another table. Example : Customers and Product Customers can purchase various products and Products can be purchased by many customers Example : Students and Courses A student can register for many Courses and a