Given this example:
In [1]: db = DAL()
In [2]: db.define_table('rel',Field('name'))
In [3]: db.define_table('rol',Field('name'),Field('parent','reference
rel'),Field('value'))
In [4]: db.rel.insert(name="Max")
In [5]: db.rel.insert(name="John")
In [6]: db.rol.insert(name="Child1", parent=1, value="DMV")
In [7]: db.rol.insert(name="Child2", parent=1, value="Suggestion")
In [8]: db.rol.insert(name="Child3", parent=2, value="DMV")
In [9]: db.rol.insert(name="Child4", parent=2, value="DMV")
You can do:
In [10]: rows =
db(db.rel.id.belongs(db(db.rol.value=='DMV')._select(db.rol.parent)))
(db.rel.id.belongs(db(db.rol.value=='Suggestion')._select(db.rol.parent))).select()
It will select Max but not John.
On Friday, 26 December 2014 01:39:12 UTC-6, Alex Glaros wrote:
>
> I have a parent (Relationship) table and a child (Role) table.
>
> Some of the child (Role) records contain the value "DMV", and other child
> (Role) records contain the value "Suggestion".
>
> I want to find a parent (Relationship) table that has Role children that
> contain both of the above values. In other words, Relationship has both a
> child that has "DMV", and another child that has the value "Suggestion".
>
> The problem is that I can't use the "or" operator because both children
> have to exist with the same parent. I can't use the "&" operator because
> the values are mutually exclusive in the same child record.
>
> To re-describe the question, here is an example of how it might be solved
> using pseudo code.
>
> FirstPass=db(Relation.id == Role.relationId) & (Role.value=="DMV")
> SecondPass=db(Relation.id == Role.relationId) & (Role.value=="Suggestion")
> ThirdPass=(FirstPass.relationId==SecondPass.relationID)
>
> Now in ThirdPass I have only the Relation records that have both "DMV" and
> "Suggestion" Role children.
>
> Thanks,
>
> Alex Glaros
>
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