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HOME ART > Tutorial > SaadaQL
A complex Example

 The example below shows an example of a full featured SaadaQL query.

Select ENTRY  From CatalogueEntry  In CATALOGUE
WherePosition {
   isInCircle("M33",1, J2000, FK5)
WhereAttributeSaada { XCAT_OBSERVER  = 'Isaac Newton' and namesaada = 'NGC598'  }
WhereAttributeClass { _obs_id > 123000}
WhereUCD { [phot.flux] < 1e-14 [erg/s/cm2] }
WhereRelation {
   matchPattern {
     , AssObjClass{ Arch_8034AEntry }
     , AssObjAttClass{_bj < 20 }
     , Qualifier{ epic_cat_dist < 1)
   matchPattern {
     , Cardinality > 1
     , AssUCD{ [src.class] = 'QSO  [none]}
     , AssObjAttSaada{ namesaada like '%q%"}

 Code explanation :

  • Select : The query will return table entries selected from dat of the class CatalogueEntry of the collection CATALOGUE
  • WherePosition Entries will be search in a 1 arcmin radius around the M33 position.
  • WhereAttributeSaada Only object named ’NGC598’ and observed by ’Isaac Newton’ will be selected. Notice that namesaada is native Saada collection attribute, wheras XCAT_OBSERVER is a collection attribute added at database creation time (see)
  • WhereAttributeClass statement can be used because the query concerns one unique class. Look at the attribute name format (begins with’_’, lowercase,....)
  • WhereUCD allows to state selection criteria withut knowing the column names (see). The list of available UCDs and units is given by the applet.
  • WhereRelation contains 2 correlation patterns. Both patterns will ANDed. Both pattern concern the same relation CatSrcToArchSrc
    • First pattern : The selected sources must have at least one counterpart of class Arch_8034AEntry with _bj less than 20 and located at less than 1 arcsec.
    • Second pattern :The selected sources must have more than one counterpart with a Saada name (collection native attribute) containing the ’q’ letter and having at least one attribute with src.class as UCD and QSO as value.
last update 2008-05-13