Re: IS OF

Can someone suggest where to document IS OF, and either document it's
non-standard behavior or supply patch?

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Joe Conway wrote:
> Gavin Sherry wrote:
> > 
> > 8.14 <type predicate> to be exact.
> > 
> 
> 8.18 in SQL200x. I don't think the current implementation quite meets 
> the spec however:
> 
> regression=# select f2 is null, f2 is of(int) from bar;
>   ?column? | ?column?
> ----------+----------
>   f        | t
>   t        | t
> (2 rows)
> 
> If I read the spec correctly, the null value should return null, not 't' 
> in the above.
> 
> General Rules
> 1) Let V be the result of evaluating the <row value predicand>.
> 2) Let ST be the set consisting of every type that is either some
>     exclusively specified type, or a subtype of some inclusively
>     specified type.
> 3) Let TPR be the result of evaluating the <type predicate>.
> 
> Case:
> a) If V is the null value, then TPR is Unknown.
> b) If the most specific type of V is a member of ST, then TPR is True .
> c) Otherwise, TPR is False
> 
> Probably best not to document it until someone gets around to fixing it 
> -- I can do it, but not for the next few weeks at least.
> 
> Joe
> 
> 
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