Lists
A list is an ordered collection of values, where the same value may occur more than once.
In Cassandra, lists are intended for
storing a small number of values of the same type. To define a list data type,
Cassandra Query Language provides construct LIST<type>, where type can refer to a CQL data type like
INT, DATE, UUID and so forth.
✅ As an example, alter table users to add column searches of type LIST<TEXT>:
ALTER TABLE users ADD searches LIST<TEXT>;
SELECT id, name, searches FROM users;
✅ Add three latest search leterals for one of the users:
UPDATE users
SET searches = [ 'Alice in Wonderland' ]
WHERE id = 7902a572-e7dc-4428-b056-0571af415df3;
UPDATE users
SET searches = searches + [ 'Comedy movies' ]
WHERE id = 7902a572-e7dc-4428-b056-0571af415df3;
UPDATE users
SET searches = searches + [ 'Alice in Wonderland' ]
WHERE id = 7902a572-e7dc-4428-b056-0571af415df3;
SELECT id, name, searches FROM users;
✅ Delete the oldest search literal and add a new one:
DELETE searches[0] FROM users
WHERE id = 7902a572-e7dc-4428-b056-0571af415df3;
UPDATE users
SET searches = searches + [ 'New releases' ]
WHERE id = 7902a572-e7dc-4428-b056-0571af415df3;
SELECT id, name, searches FROM users;
✅ Next, alter table users to add column emails and
add two email addresses for one of the users:
Solution
ALTER TABLE users ADD emails LIST<TEXT>;
UPDATE users
SET emails = [ 'joe@datastax.com',
'joseph@datastax.com' ]
WHERE id = 7902a572-e7dc-4428-b056-0571af415df3;
SELECT id, name, emails FROM users;