Re: [Boost-users] SQL library with full embedded SQL-syntax

From: Christian Henning (chhenning_at_[hidden])
Date: 2007-03-15 12:12:37

> > I like and use SOCI, as well. Although, today I found out about
> > litesql and I like their approach of generating c++ code from xml
> > based table definitions. So, I think a cross of both would be nice.
>
> Interesting, but this seems fairly limited to a very specific mapping.  What
> if I need to change the mapping names or key associations? And, I have come
> out of the closet -- I hate xml as a primary 'input language'.  If you're
> going to all the trouble of writing a generator, why not write one with
> simplified data specification language?
>
OK, admittedly I'm not a db professional but changing the mapping in
runtime? Isn't this like asking for trouble?

Does a simplified data specification language exist?

Another idea is have a graph representation of the model in memory.
Something like using boost::graph, maybe?

> Off the top of my head -- imagine something like more like this:
>
> schema example {
>    type Mother; //forward declare
>    type Father;
>    type Office;
>
>    type Role {};
>    type Employee : Role {
>       //1 to many bi-directional, required
>       Office office  <-> employees[0..*];
>    }
>    type Office {
>        Employee employees[0..*] <-> office; //needs to match Employee
>    }
>
>    type Student : Role {
>    }
>
>    type School {
>       string name;
>    }
>
>    //alternative way to specify a relation outside the type
>    //Student will have an optional relation to school
>    //School will have 0 to many students
>    relation StudentSchool {
>        Student.school[0..1] <-> School.students[0..*];
>    }
>
>    enum Sex { Male=0, Female=1 };
>
>    //The obvious mapping Table = Person
>    type Person {
>      string  name;  //mapped to column name in table Person
>      Sex     sex;
>      integer age = 0;
>      //automatically generates Table PersonRoles
>      Role    roles[0..*]; //unidirectional 0..m relation
>      //Generates a field for mother id
>      Person  mother;  //unidirectional required relation
>      Person  father;
>      //automatically generates a join table PersonSiblings
>      Person  siblings[0..*] <-> siblings[0..*];//bidirectional m-m
>    };
>
> }
>
> database Exampledb uses schema example;
>
Looks nice it that coming from your imagination only? ;-)

Christian