Data types¶

Each column in relational databases has a specific type that defines exactly what kind of data can be stored in it. These types can be divided into 3 groups:

numerical
date and time
chain.

Numeric types¶

SQL numeric types

String types¶

SQL string types

Date and time¶

SQL date and time types

NOTE: Depending on the specific database implementation and version, the database may not offer certain data types, or be specific types only for its implementation.

NOTE: Depending on the specific database implementation and version, the length or size of the database type may vary.

Null value¶

Databases also offer the possibility of representing a blank value, which can be presented in a column of a table. This value is tagged with the keyword NULL.