Creating a user-defined type (UDT)

User-Defined Types (UDTs) can be used to attach multiple data fields to a column.

In Cassandra 2.1 and later, user-defined types (UDTs) can attach multiple data fields, each named and typed, to a single column. The fields used to create a UDT may be any valid data type, including collections and other existing UDTs. Once created, UDTs may be used to define a column in a table.

Procedure

Use the cycling keyspace.
```
cqlsh> USE cycling;
```

Create a user-defined type named basic_info.

cqlsh> CREATE TYPE cycling.basic_info (
  birthday timestamp,
  nationality text,
  weight text,
  height text
);

Create a table for storing cyclist data in columns of type basic_info. Use the frozen keyword in the definition of the user-defined type column. In Cassandra 3.6 and later, the frozen keyword is not required for UDTs that contain only non-collection fields.
When using the frozen keyword, you cannot update parts of a user-defined type value. The entire value must be overwritten. Cassandra treats the value of a frozen, user-defined type like a blob.
```
cqlsh> CREATE TABLE cycling.cyclist_stats ( id uuid PRIMARY KEY, lastname text, basics FROZEN<basic_info>);  
```

A user-defined type can be nested in another column type. This example nests a UDT in a list.

CREATE TYPE cycling.race (race_title text, race_date timestamp, race_time text);
CREATE TABLE cycling.cyclist_races ( id UUID PRIMARY KEY, lastname text, firstname text, races list<FROZEN <race>> );