ZSQLCatalog is an extension to the traditional Zope ZCatalog and Indexes. It currently implements an Index which uses an SQL database as external storage. It allows to query a Zope Catalog with a combination of traditional Zope Catalog queries (field based, text based) and with complex queries implemented as SQL methods.

By using ZSQLCatalog, it is possible to develop a whole system with an object oriented approach and forget about external relational databases yet provide to users the usual experience of SQL queries.

This Zope product was implemented as a subproject of the ERP5 project in order to add complex queries to the Zope Object Database without using an external database for attributes storage.

It is currently much of a "proof-of-concept" which needs to be extended. Future versions will include greater flexibility, will implement relations and provide more options for external storage of indices (ex. use of an LDAP directory to store indices).