3 ms·

There's no reason ever to use a right join. I consider those to be a code smell.

• sesqu 15y ago
  There's about as much reason to use a right join as there is to use a left join.
  • endersshadow 15y ago
    I don't think I've ever used a right join in a production query (perhaps a couple of times when I was doing some digging and it was easier), but I don't understand your statement. Left joins are insanely useful. For example, getting all the sales for a salesperson: select sp.Name, sum(s.Amount) as TotalSales from SalesPerson sp left join Sales s on sp.SalesPersonKey = s.SalesPersonKey group by sp.Name order by TotalSales desc If you did a correlated subquery, it would take a ton of time to complete (`select sum(Amount) from Sales s where s.SalesPersonKey = sp.SalesPersonKey`), especially on large tables. Left joins (and full outer joins) are plenty useful and I use them almost daily. Care to explain what you mean?
    • ckuehne 15y ago
      What he (probably) means is that the following query returns the same result as your query: select sp.Name, sum(s.Amount) as TotalSales from Sales s RIGHT join SalesPerson sp on sp.SalesPersonKey = s.SalesPersonKey group by sp.Name order by TotalSales desc EDIT: Formatting.
      • jtheory 15y ago
        That's what was meant, I assume, but it's misguided. Right joins don't create a "code smell" for technical reasons, but for practical reasons. Because left joins are the standard approach, if you're using a non-standard approach to a common problem you'd better have a damned good reason (because you're just confusing maintenance programmers... and thus causing errors... with no justification, otherwise).
  • bhousel 15y ago
    Yes, but one of them means that you're thinking about the problem backwards.
• gnaritas 15y ago
  Ditto.
• og1 15y ago
  Agree with this as well. Forgot exactly what one was and googled it to make sure. The example that is used here would indicate orphaned records. http://www.w3schools.com/sql/sql_join_right.asp http://www.w3schools.com/sql/sql_join_right.asp
  • ceejayoz 15y ago
    There are valid use cases for orphaned records. A quote database might want to allow registered and anonymous submission, for example.
    • derefr 15y ago
      Or, ala Reddit, comments from deleted users.