In the preceding chapters, we focused largely on the high-level structure of Cassandra tables and particularly on the forms and uses of primary keys. Now we will turn our focus to the data that's stored within tables, exploring advanced techniques to add, change, and remove data.
Previously, we created several tables in the MyStatus application, but so far, we haven't made any changes to those tables' schemas. In this chapter, we'll introduce the ALTER TABLE statement, which enables us to add and remove columns from the tables in our keyspace.
We'll move on to the UPDATE statement, which is used to change the data in existing rows. You'll learn that INSERT and UPDATE have more in common than our experience with relational databases might lead us to believe, and that INSERT, in particular, can have unexpected and undesirable effects if not used carefully. We'll also expand our understanding of the DELETE statement, using it to remove data from specific columns...