Database table
A database table is a collection of related data that is stored in a database in a structured format . It consists of columns and rows. The number of columns is fixed, the number of rows is arbitrary.
Database tables in relational databases
Database tables play an important role in the context of relational databases . A database table represents a database relation . The relation is the namesake and basis of the relational databases.
The rows are called tuples , the columns are called attributes. The description of the database table is the relation schema and defines the type of attributes. A database table can contain so-called primary keys , which consist of one or more attributes. A primary key is a unique name for a data record. In addition to the primary key, it can contain foreign keys that refer to the primary key or, in rare cases, other attributes of another table. A table that does not contain foreign keys is called a "flat table".
Example of creating a database table in SQL:
CREATE TABLE buecher (
Buchnummer int PRIMARY KEY,
Autor varchar(80),
Verlag varchar(80),
Verlagsjahr int,
Titel varchar(250),
Datum date
);
Example for the contents of the previously created database table:
Book number | author | publishing company | Publishing year | title | date |
---|---|---|---|---|---|
123456 | Hans prolific writer | Sample publisher | 2007 | We learn SQL | 13/01/2007 |
123457 | J. Gutenberg | Gutenberg and Co. | 1452 | Printing made easy | 01/01/1452 |
123458 | Galileo Galilei | Inquisition International | 1640 | Eppur si muove | 1641 |
123459 | Charles Darwin | Vatican Publishing House | 1860 | Adam and Eve | 1862 |
See also
- Scheme (computer science) - formal description of the structure of data