Relational Database Management System (R DBMS). Revise definitions related to database.
Database:- A database is a collection of tables, with related data.
Table:- A table is a matrix with data. A table in a database looks like a simple spreadsheet.
Column:- One column (data element) contains data of one and the same kind, for example the column postcode.
Row:- A row (tuple, entry or record) is a group of related data, for example the data of one subscription.
Redundancy:- Storing data twice, redundantly to make the system faster.
Primary key:- A primary key is unique. A key value can not occur twice in one table. With a key, you con find at most one row.
Foreign key:- A foreign key is the linking pin between two tables.
compound key:- A compound key (composite key) is a key that consists of multiple columns, because one column is not sufficiently unique.
Index:- An Index in a database resembles an index at the back of a book.
Referential integrity:- Referential Integrity makes sure that a foreign key value always points to an existing row.