SQL for Data Analytics - Fourth Edition
by Jun Shan, Haibin Li, Matt Goldwasser, Upom Malik, Benjamin Johnston
6
Transforming and Updating Data
In previous chapters, you learned how to populate data using different commands and statements. As data enters a table, it is common that you will need to change some of the values. First of all, the source data may change. A customer may move to a new address. An employee may get a promotion. The changes in the real world require changes in the tables. Existing data may also need corrections or updates, such as correcting a typo during data entry time. That’s why update is such an important operation in the data CRUD (short for create, read, update, delete) lifecycle.
The change may happen not only to table data but also to table structures. Tables are a reflection of entities and relationships in the real world. ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access