Inner Joins are the most common type of Joins. Inner joins match records together where values are equal on both sides of the join statement.
INNER JOINs are the backbone of advanced SQL querying. There are literally thousands of books, articles and blog posts with examples and information about SQL joins.
In the video, we only showed two tables being joined together, but in reality, you can join in any number of tables.
If all tables are inner-joined together, the resulting data set will contain only rows that match on the specified relationships throughout all tables. The resulting Venn Diagram could get quite complex, and depends on many factors, including number of tables, and relationships used, but could look something like this:
See all of the SQL used in Querying Relational Databases in the Querying Relational Databases Cheat Sheet.
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