Job-Ready SQL in an Afternoon - Left, Right, and Outer Joins

The video tutorial explains different types of SQL joins, including inner, left, right, and full outer joins. It demonstrates how to count unique tracks using the distinct keyword and discusses the implications of using different joins on data retention and table size. The tutorial emphasizes the importance of choosing the right join type based on the data analysis needs, highlighting the differences between retaining unmatched data and focusing on intersections.

What is the primary purpose of using joins in SQL?

• To create new tables

• To update data in tables

• To find the intersection between tables

• To delete data from tables

In the context of SQL, what does the DISTINCT keyword do?

• It sorts the data

• It looks for unique occurrences

• It finds the sum of values

• It counts all occurrences

Why might you use a left join instead of an inner join?

• To retain all data from the first table even if there's no match

• To discard all unmatched data

• To only keep data from the second table

• To increase the size of the resulting table

What happens to unmatched rows in a left join?

• They are deleted

• They are moved to a new table

• They are filled with nulls

• They are duplicated

How does a right join differ from a left join?

• It discards all null values

• It only keeps data from the first table

• It keeps all data from the second table

• It is the same as an inner join

What is a full outer join used for?

• To sort data from both tables

• To delete unmatched data

• To keep all data from both tables, filling nulls where necessary

• To keep only the intersection of two tables

Which join type would you use to ensure no data is lost from either table?

• Left join

• Inner join

• Right join

• Full outer join

What is a potential downside of using left or right joins?

• They delete unmatched data

• They can result in larger tables

• They only work with numeric data

• They always decrease table size

When should you consider using an inner join?

• When you want to keep all data from both tables

• When you need to update data in both tables

• When you only need the intersection of two tables

• When you want to discard all data

What should you consider when choosing a join type?

• The color of the tables

• The number of columns

• The type of database

• The size and data retention needs