Wie zu beheben Kein Datentyp für Knoten Fehler in hibernate

Ich habe die Tabelle Fahrzeug ,das habe ich geschrieben-Abfrage, wie unten

Fahrzeug.executeQuery("select audio_system vom Fahrzeug ")
aber ich erhalte eine Fehlermeldung

FEHLER groovy.grails.web.Fehler.GrailsExceptionResolver ### Kein Datentyp für Knoten: org.hibernate.hql.ast.Baum.IdentNode
-[IDENT] IdentNode: 'audio_system' {originalText=audio_system}

java.lang.IllegalStateException: No Datentyp für Knoten: org.hibernate.hql.ast.Baum.IdentNode
-[IDENT] IdentNode: 'audio_system' {originalText=audio_system}

Source-code von der Fahrzeugklasse wie folgt

class Vehicle {


    String vehicleSticker
    String regNumber //plate
    String chasisNumber
    String engineNumber
    Integer yearOfManufacture
    Date purchasedOn

    Boolean audioSystem
    Boolean videoSystem
    Boolean mobileCharger
    Boolean laptopCharger

    //Vehicle compliance
    Date pucExpiry
    Date pucTestingOn
    Date taxTokenIssueDate
    Date taxTokenExpiryDate
    Date insuranceIssueDate
    Date insuranceExpiryDate
    Date permitIssueDate
    Date permitExpiryDate
    Date fitnessCertificateIssueDate
    Date fitnessCertificateExpiryDate
    Double odoReadingWhenServiceDone
    Double dueOddReading

    VendorRole vendor

    VehicleType vehicleType
    //RegistrationCertificate registrationCertificate

    static mapping = {
        //registrationCertificate(cascade:'all')

    }

    static constraints = {
        yearOfManufacture(nullable:true)
        regNumber(nullable:false,unique: true)
        chasisNumber(blank:true)
        engineNumber(blank:true)
        purchasedOn(nullable:true)
        taxTokenIssueDate(nullable:true)
        taxTokenExpiryDate(nullable:true)

        insuranceIssueDate(nullable:true)
        insuranceExpiryDate(nullable:true)
        permitIssueDate(nullable:true)
        permitExpiryDate(nullable:true)
        fitnessCertificateIssueDate(nullable:true)
        fitnessCertificateExpiryDate(nullable:true)
        odoReadingWhenServiceDone(nullable:true)

        dueOddReading(nullable:true)
        pucExpiry(nullable:true)
        pucTestingOn(nullable:true)

        vendor(nullable:true)


    }

    public String toString() {
        "${vehicleSticker} ${regNumber?'| '+ regNumber:''}"
    }