SQL xlat and multivalued attributes

[Alan DeKok]

Phil Mayers wrote:
> Alternatively, just enforce that the SQL query has to return:
> 
> select attrname, op, val from ...
> 
> ...i.e. returning
> 
> request:Foo | := | bar
> reply:Class | := | baz

  That's pretty much what Arran and I ended up with.  The downside is
that we'll have to create a new internal expansion API, as the current
one only deals with strings.

  Then the question becomes what syntax to use, to signal using the new
expansion.

  The input is a string, containing an SQL "select" statement.  The
output is a list of VPs.  So... the only syntax I can thing of which
makes sense is:

	update {
		reply += "%{sql:SELECT ...}"
	}

  i.e. when the destination is a list, the new expansion function is
used, instead of the old on.  This is easy to discover in the code.

  This syntax is similar to what Arran already added:

	update {
		reply += `/path/to/program`
	}

  So there's precedent.

  I think that functionality will be very useful.  I know in the systems
I build, I sometimes have to go through contortions to get multiple
fields out of SQL and into attributes.

  Alan DeKok.