Question

You don't ever need to code a right outer join because

1. left outer joins are easier to code
2. right outer joins are less efficient
3. left outer joins are just as efficient
4. right outer joins can be converted to left outer joins

Answer 1

The subject is SQL joins, specifically the difference between LEFT OUTER JOIN and RIGHT OUTER JOIN. Right outer joins can be converted to left outer joins by changing the order of the tables and join type, which is why you might not need to code right outer joins.

Step-by-step explanation:

The question pertains to the concept of SQL joins, which are used in relational database management systems to combine rows from different tables based on a related column between them. Specifically, it addresses the difference between LEFT OUTER JOIN and RIGHT OUTER JOIN. In SQL, a right outer join includes all records from the right table (table2), and the matched records from the left table (table1). If there is no match, the result is NULL on the left side.

While both types of joins are designed to serve specific needs depending on the data retrieval requirements, it is often said that you do not need to code a right outer join because it can indeed be converted into a left outer join, which may be more familiar to many developers. The conversion can be achieved by simply swapping the order of the tables in the join and changing the join type from right to left. It is not that right outer joins are less efficient or that left outer joins are inherently easier to code, but rather, it is a matter of personal or organizational preference and the specific requirements of the database query. The efficiency of these joins depends on many factors, including database engine optimization, indexes, and the specific data distribution.