Load - Save problem

[Nobody/Anonymous]

I created new object, set its' fields with data and saved it.
So I now have record in DB that contains fields of my object and createdDate with date but modifiedDate with null value.
The problem is:
obj.Retrieve(); - ok obj fields are populated. but obj.m_modifiedDate has Now value.
obj.name = newName;
obj.Save(); - tries to save :UPDATE SculptureType SET nameRu=?, nameEn=?, createYear=?, meter=?, picture=?, patina=?, material=?, createdDate=?, modifiedDate=? WHERE  SculptureType.id = ? AND SculptureType.createdDate = ? AND SculptureType.modifiedDate = ? ;

Got problem? modifiedDate in DB is null, but in obj it is Now.
So no records is updated.
What is wrong?
Here the Class code:

public class SculptureType : CPersistentObject
    {
        private long _id;
        private string _nameRu;
        private string _nameEn;
        private string _createYear;
        private string _meter;
        private string _picture;
        private string _patina;
        private string _material;

        #region Properties

        public long id
        {
            get { return _id; }
            set
            {
                if(_id!=value)
                {
                    _id = value;
                    SetDirtyFlag();
                }
            }
        }

        public string nameRu
        {
            get { return _nameRu; }
            set
            {
                if(!string.Equals(_nameRu, value))
                {
                 _nameRu = value;
                 SetDirtyFlag();
                }
            }
        }

        public string nameEn
        {
            get { return _nameEn; }
            set
            {
                if(!string.Equals(_nameEn, value))
                {
                    _nameEn = value;
                    SetDirtyFlag();
                }
            }
        }

        public string createYear
        {
            get { return _createYear; }
            set
            {
                if(!string.Equals(_createYear, value))
                {
                    _createYear = value;
                    SetDirtyFlag();
                }
            }
        }

        public string meter
        {
            get { return _meter; }
            set
            {
                if(!string.Equals(_meter,value))
                {
                    _meter = value;
                    SetDirtyFlag();
                }
            }
        }

        public string picture
        {
            get { return _picture; }
            set
            {
                if(!string.Equals(_picture,value) )
                {
                    _picture = value;
                    SetDirtyFlag();
                }
            }
        }

        public string patina
        {
            get { return _patina; }
            set
            {
                if(!string.Equals(_patina,value))
                {
                    _patina = value;
                    SetDirtyFlag();
                }
            }
        }

        public string material
        {
            get { return _material; }
            set
            {
                if(!string.Equals(_material, value))
                {
                    _material = value;
                    SetDirtyFlag();
                }
            }
        }
       
        #endregion

        public SculptureType()
        {
            //
            // TODO: Add constructor logic here
            //
            //_id = 0;
        }

        public override CPersistentObject getNewObject()
        {
            return new SculptureType();
        }

        public override bool IsValid()
        {
            //TODO: this method should check object state is ready to be saved in database
            return true;
        }

        public override string ToString()
        {
            string pattern = "SculptureType [id={0}; nameRu={1}; nameEn={2}; createYear={3}; meter={4}; picture={5}; patina={6}; material={7};]";
            return string.Format(pattern, new string[]{_id.ToString(), _nameRu, _nameEn, _createYear, _meter, _picture, _patina, _material});
        }
    }

Mapping:

<?xml version="1.0" encoding="utf-8" ?>
<map>
  <database name="base" class="CMsAccessDatabase">
    <parameter name="name" value="base.mdb" />         
  </database>
 
  <class name="SculptureType" table="SculptureType" database="base">
    <attribute name="id" column="id" key="primary" find="true" identity="true"/>
    <attribute name="nameRu" column="nameRu" proxy="true"/>
    <attribute name="nameEn" column="nameEn" proxy="true"/>
    <attribute name="createYear" column="createYear" />
    <attribute name="meter" column="meter" />
    <attribute name="picture" column="picture" />
    <attribute name="patina" column="patina" />
    <attribute name="material" column="material" />   
    <attribute name="createdDate" column="createdDate" timestamp="true"/>
    <attribute name="modifiedDate" column="modifiedDate" timestamp="true"/>   
  </class> .....

And Run Code:

SculptureType type = new SculptureType();
CPersistenceBroker pbroker = new CPersistenceBroker();
pbroker.init();
type.id = 4;
type.Retrieve();
type.nameRu = "New name";
type.Save(); - here I got zero records were updated exception

Thanks in advance,
Denis -SWE

[Nobody/Anonymous]

The problem was n handling nulls in query. After I have added to database config
<parameter name="ansinulls" value="true"/>      
the update query gets correct IS NULL  - null handling