Differences between Inner Join and Outer Join in Oracle SQL

An inner join in Oracle SQL is used to retrieve rows from both tables that have matching values based on the specified join condition. It only returns the rows where there is a match between the columns being joined.

On the other hand, an outer join in Oracle SQL is used to retrieve all rows from one table and only the matching rows from the other table based on the specified join condition. There are three types of outer joins: left outer join, right outer join, and full outer join.

When to Use Each Type of Join:

• Inner Join: Use an inner join when you only want to retrieve rows that have matching values in both tables. This is typically used when you are looking for records that appear in both tables.
• Left Outer Join: Use a left outer join when you want to retrieve all rows from the left table and the matching rows from the right table. This is useful when you want to include all records from one table, even if there are no matches in the other table.
• Right Outer Join: Use a right outer join when you want to retrieve all rows from the right table and the matching rows from the left table. This is the opposite of a left outer join.
• Full Outer Join: Use a full outer join when you want to retrieve all rows from both tables, regardless of whether there are matching values. This includes all records from both tables, with NULL values where there is no match.