Re:What's the strangest code you've seen a senior developer ...
by denton-scratch on Sunday March 27, 2022 @10:29AM
(#30820498)
I'm old too.
As far as I'm concerned, LEFT JOIN is simply shorthand for LEFT OUTER JOIN, and is semantically equivalent to a RIGHT JOIN, but with the order of the tables reversed. If what you really need is an INNER JOIN, and you use a LEFT JOIN instead, then you have a load of processing to do on the result-set.
So if this guru "Jared" is only ever using LEFT JOIN, then either he's addressing a rather constrained problem space, or he's isn't that much of a SQL guru. Maybe he designs schemas in which LEFT joins are always equivalent to INNER joins?
[Edit] I'm wrong; you can, of course, get the effect of an INNER JOIN by using a LEFT JOIN with a NOT NULL join condition. But I find the latter hard to read: there must be some reason this guy has used an outer join here, when it looks as if an inner join fits the bill?
As far as I'm concerned, LEFT JOIN is simply shorthand for LEFT OUTER JOIN, and is semantically equivalent to a RIGHT JOIN, but with the order of the tables reversed. If what you really need is an INNER JOIN, and you use a LEFT JOIN instead, then you have a load of processing to do on the result-set.
So if this guru "Jared" is only ever using LEFT JOIN, then either he's addressing a rather constrained problem space, or he's isn't that much of a SQL guru. Maybe he designs schemas in which LEFT joins are always equivalent to INNER joins?
[Edit] I'm wrong; you can, of course, get the effect of an INNER JOIN by using a LEFT JOIN with a NOT NULL join condition. But I find the latter hard to read: there must be some reason this guy has used an outer join here, when it looks as if an inner join fits the bill?