Chapter 3. Querying from Multiple Tables
Querying data from Oracle tables is probably the most common task you will perform as a developer or data analyst, and maybe even as a DBA—though probably not as the ETL (Extraction, Transformation, and Loading) tool expert. Quite often, you may query only one table for a small subset of rows, but sooner or later you will have to join multiple tables together. That's the beauty of a relational database, where the access paths to the data are not fixed: you can join tables that have common columns, or even tables that do not have common columns (at your own peril!).
In this chapter we'll cover solutions for joining two or more tables and retrieving the results based on the existence of desired rows in both ...
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