24.4.4 Merging Data from Multiple Tables: INNER JOIN
Database designers often split related data into separate tables to ensure that a database does not store data redundantly. For example, in the books database, we use an AuthorISBN table to store the relationship data between authors and their corresponding titles. If we did not separate this information into individual tables, we’d need to include author information with each entry in the Titles table. This would result in the database’s storing duplicate author information for authors who wrote multiple books. Often, it’s necessary to merge data from multiple tables into a single result. Referred to as joining the tables, this is specified by an INNER JOIN operator, which merges rows from ...
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