Data Types¶

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

numerical
date and time
string.

Numeric types¶

SQL numeric types

String types¶

SQL string types

Date and time¶

SQL date and time types

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

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

Empty value¶

Databases also offer the option of representing an empty value, which can be found, for example, in a table column. This value is identified by the keyword NULL.