| name = {{PAGENAME}}
| internalname = SystemObjects.{{PAGENAME}}
| namespace = System.Query<br/>Custom.Query
| image = [[File:SY_QUERY.png|220px]]
| imagecaption = Query
== Query and QueryItems ==
A Query is defined for a single [[MetaClass]], where the MetaClass is defined in the property '''FILTEROBJECT'''. Once a query is evaluated it will deliver a list of objects of type ContentClasses (instances), filtered as defined by its [[QUERYITEM|QueryItems]].
== Relation between Query and Items ==
The correspondence between Queries and its items is created and stored by a relationship [[SYSREL_QUERY]]. Therefore a single QueryItem can be used several times for different Queries.
==Content queriesquery ==We often face the need to fetch Fetching a list of objects meeting arbitary filtered by certain criteria, for example for
* scanning of ID markers (QR-Code, Barcode, …)
* show objects from deeper hierarchy levels
* Create and relate a query context scope and set the instance as QUERY
* For the scope define the MetaProperties, which should be available as filter criteria on the client. Without appropriate query item, equality is used as filter operator (=)
== Scan query ==
== Usage of DatabaseViews ==