Question

What is the difference between Left join vs Right join vs Inner join?

Answer 1

The main differences between left join, right join, and inner join in SQL are based on which rows from the involved tables are returned in the query results. No join is more correct than another; the choice depends on the desired outcome of the query.

Step-by-step explanation:

Differences Between Left Join, Right Join, and Inner Join

When dealing with SQL database queries, joins are used to retrieve data from two or more tables based on a related column between them. The differences between left join, right join, and inner join are primarily about which rows are included in the resulting data set:

• Left Join (or Left Outer Join): Returns all rows from the left table, and the matched rows from the right table. If there is no match, the result is NULL on the right side.
• Right Join (or Right Outer Join): Returns all rows from the right table, and the matched rows from the left table. If there is no match, the result is NULL on the left side.
• Inner Join: Returns rows when there is at least one match in both tables.

Addressing the questions

1. No table is inherently more correct than the other. The choice of which join to use depends on the requirements of the query and the desired results.
2. Grouping data differently could mean using different types of joins, or even combining them. The advantages of each method depend on the context of the data and what information is required.
3. Switching between tables in a query allows for a nuanced retrieval of data and depends on the relationships between the data entities and the analysis goals.