Check Any record exists in given date Range while inserting a record

In Validate write of Table or Form Datasource

public boolean validateWrite()
{
    boolean                     ret;
    SCPProductPossessionCharges scpProductPossessionChargesloc;

    if (SCPProductPossessionCharges.FromDate > SCPProductPossessionCharges.ToDate)
    {
        error("@GLS90176");
        return false;
    }

  while select scpProductPossessionChargesloc
       where scpProductPossessionChargesloc.ItemId == SCPProductPossessionCharges.ItemId
          && scpProductPossessionChargesloc.SCPPossessionCharges == SCPProductPossessionCharges.SCPPossessionCharges
          && scpProductPossessionChargesloc.RecId != SCPProductPossessionCharges.RecId
    {
       ret = element.checkDateOverlap(SCPProductPossessionCharges,scpProductPossessionChargesloc);
        if(!ret)
        {
            error("@SCP353");//A record already exists for given date range
            return ret;
        }
    }

    ret = super();

    return ret;
}


one public method checkDateOverlap(newrecord,existingRecord)

public boolean checkDateOverlap(
    scpProductPossessionCharges _curVersion ,
    scpProductPossessionCharges _checkAgainstVersion )
{

        if ((_curVersion.ToDate   >= _checkAgainstVersion.FromDate || !_curVersion.ToDate) &&
            (_curVersion.FromDate <= _checkAgainstVersion.ToDate   || !_checkAgainstVersion.ToDate))
        {
            return false;
        }

        if (   _checkAgainstVersion.ToDate   >= _curVersion.FromDate
            && _checkAgainstVersion.FromDate <= _curVersion.ToDate)
        {
            return false;
        }


    return true;

}