Introduction

------------

Goals of RQL

~~~~~~~~~~~~

The goal is to have a language emphasizing the way of browsing

relations. As such, attributes will be regarded as cases of

special relations (in terms of implementation, the language

user should see virtually no difference between an attribute and a

relation).

`CubicWeb` schema defining the application is necessary.

Comparison with existing languages

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

SQL

```

RQL builds on the features of SQL but is at a higher level

(the current implementation of RQL generates SQL). For that it is limited

schema defining the application.

Versa

`````

We should look in more detail, but here are already some ideas for

the moment ... Versa_ is the language most similar to what we wanted

to do, but the model underlying data being RDF, there is some

does not interest us. On the functionality level, Versa_ is very comprehensive

including through many functions of conversion and basic types manipulation,

Finally, the syntax is a little esoteric.

Sparql

``````

The query language most similar to RQL is SPARQL_, defined by the W3C to serve

The different types of queries

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Search (`Any`)

   Extract entities and attributes of entities.

Insert entities (`INSERT`)

   Insert new entities or relations in the database.

   It can also directly create relationships for the newly created entities.

Update entities, create relations (`SET`)

   Update existing entities in the database,

   or create relations between existing entities.

Delete entities or relationship (`DELETE`)

   Remove entities or relations existing in the database.

.. _Versa: http://uche.ogbuji.net/tech/rdf/versa/

.. _SPARQL: http://www.w3.org/TR/rdf-sparql-query/