Defining a primary key column
The only schema information that must be defined for a table is the primary key and its associated data type. Unlike earlier versions, CQL does not require a column in the table that is not part of the primary key. A primary key can have any number (1 or more) of component columns.
If the primary key consists of only one column, you can use the keywords, PRIMARY KEY, after the column definition:
CREATE TABLE users ( user_name varchar PRIMARY KEY, password varchar, gender varchar, session_token varchar, state varchar, birth_year bigint );
Alternatively, you can declare the primary key consisting of only one column in the same way as you declare a compound primary key. Do not use a counter column for a key.