Relational databases. Data types. Attributes and tuples.
Relational database is a type of database that is structured and allows users to identify and access data which is in relation to other data.
A relational database is a collection of data with predefined relationships between them. Database data is organized as a set of tables, consisting of columns and rows. The tables store information about the entities represented in the database. Each column of the table stores a specific data type, each cell contains the value of an attribute. Each table is a collection of related values that refer to a single object or entity. Each row in a table can be labeled with a unique identifier called a primary key, and rows from multiple tables can be linked using foreign keys. This data can be accessed in many ways, without the need to reorganize the database tables.
Table stores all of the records for a particular category.
Entity is an item that is represented in a database.
Field (Attribute) this is a single piece of data such as name, date of birth or telephone number.
Record (Tuple) is all of the data or information about one person or one thing.
Index a values of key field that help database management system to find and sort records quickly.
A primary key is a field in a table that contains unique data. Primary key is the unique identifier for each record in a table. A primary is a single column value used to identify a database record uniquely.
Foreign key is a field in one table that is linked to the primary key in another table.
Composite key - сollection of attributes uniquely identify a tuple rather than just one.