How does a LEFT JOIN differ from an INNER JOIN?

A LEFT JOIN is a type of join that retrieves all records from the left table in the query while also including the matching records from the right table. If there are no matches found in the right table, the LEFT JOIN still provides all the rows from the left table, with the corresponding values from the right table appearing as NULL. This ensures that you retain all data from the left table, which can be particularly useful when you want to ensure that you capture all instances from that dataset regardless of their relationship to the right table.

In contrast, an INNER JOIN exclusively returns rows where there is a match in both tables. Therefore, if there are no matching entries in either table, those rows will be excluded entirely from the results. This significant difference highlights the utility of the LEFT JOIN in data analysis when you want to maintain the integrity of one dataset while also appending data from another when it exists.