Business Artifacts have recently emerged as a compelling paradigm to develop data-centric processes, supporting flexible and knowledge intensive business processes. Artifact-centric process models, as an alternative to predefined activity-centric process models, are easy to be understood and managed by non-IT specialists. Artifacts are also complex entities, which include information models, states, services and transition rules. They interact with each other, updating their information models and evolve following their lifecycles. Despite the increasing glamour that was raised on artifacts from research and business communities, the lack of expressive languages to manipulate and interrogate them, limits their widespread usage. In this paper, we define a declarative Artifact Query Language (AQL) that relies on a relational schema to define, manipulate, and query artifact types. The AQL takes full-advantage of the well-established SQL to manipulate the relational schema and relieves casual users from the need to directly deal with SQL’s statements and the underlying relational model (i.e., relations, keys constraints, and constructing complex queries).