Perfect. Thanks for your time.

Jason

Ann W. Harrison wrote:

> Jason,
>
> Flattery will get you a long way - though Helen is the real expert
> in this area, in my opinion. The SQL-89 join syntax is OK if all your
> joins are inner joins and you never mix the syntaxes.
>
> In other words, this is old-fashioned but OK:
>
> select ... from t1 x, t2 y, t3 z
> where x.a = y.b and y.a = z. b
>
> this is not good:
>
> select ... from t1 x
> inner join t2 y, t3 z on x.a = y.b
> where y.a = z.b
>
> this is very bad:
>
> select ... from t1 x
> left outer join t2 y, t3 z on x.a = y.b
> where y.a = z.b
>
> and this is terrible:
>
> select ... from t1 x, t2 y
> left outer join t3 z on y.a = z.b
> where x.a = y.b
>
> The problem is that there is a required precedence between the SQL-89
> type join and the inner and outer SQL-92 joins that affects the
> optimizer's ability to distribute equalities and perform filtering on
> the input streams at the initial phases of the join. Those abilities
> are critical to good performance. The precedence can also trip up the
> logic of the query, leading to unexpected, but not inexplicable results.
>
> So, to answer your question, using the SQL-89 joins in program (or
> procedure) code is a lazy practice that shows a lack of willingness to
> learn and very little consideration for the people who will inherit the
> code. It also leads to poor performance and unexpected results.
>
> Personally, I no longer write SQL-89 joins except in interactive tools
> and change code that uses that join type as I find it.
>
>
> Is that clear?
>
>
> Cheers,
>
>
> Ann
>
>
>
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