I can not resolve this error in SugarCRM

Question

this is my coding project.php:

class Project extends SugarBean { // database table columns

var $id;
var $date_entered;
var $date_modified;
var $assigned_user_id;
var $modified_user_id;
var $created_by;
var $name;
var $description;
var $deleted;


// related information
var $assigned_user_name;
var $modified_by_name;
var $created_by_name;

var $account_id;
var $contact_id;
var $opportunity_id;
var $email_id;
var $estimated_start_date;

// calculated information
var $total_estimated_effort;
var $total_actual_effort;

var $object_name = 'Project';
var $module_dir = 'Project';
var $new_schema = true;
var $table_name = 'project';
var $importable = true;

// This is used to retrieve related fields from form posts.
var $additional_column_fields = array(
    'account_id',
    'contact_id',
    'opportunity_id',
);

var $relationship_fields = array(
    'account_id' => 'accounts',
    'contact_id'=>'contacts',
    'opportunity_id'=>'opportunities',
    'email_id' => 'emails',
);

//////////////////////////////////////////////////////////////////
// METHODS
//////////////////////////////////////////////////////////////////

/**
 *
 */
function Project()
{
    parent::SugarBean();
}

/**
 * overriding the base class function to do a join with users table
 */

/**
 *
 */
function fill_in_additional_detail_fields()
{
    parent::fill_in_additional_detail_fields();

    $this->assigned_user_name = get_assigned_user_name($this->assigned_user_id);
    //$this->total_estimated_effort = $this->_get_total_estimated_effort($this->id);
    //$this->total_actual_effort = $this->_get_total_actual_effort($this->id);
}

/**
 *
 */
function fill_in_additional_list_fields()
{
    parent::fill_in_additional_list_fields();
    $this->assigned_user_name = get_assigned_user_name($this->assigned_user_id);
    //$this->total_estimated_effort = $this->_get_total_estimated_effort($this->id);
    //$this->total_actual_effort = $this->_get_total_actual_effort($this->id);
}

/**
* Save changes that have been made to a relationship.
*
* @param $is_update true if this save is an update.
*/
function save_relationship_changes($is_update, $exclude=array())
{
    parent::save_relationship_changes($is_update, $exclude);
    $new_rel_id = false;
    $new_rel_link = false;
    //this allows us to dynamically relate modules without adding it to the relationship_fields array
    if(!empty($_REQUEST['relate_id']) && !in_array($_REQUEST['relate_to'], $exclude) && $_REQUEST['relate_id'] != $this->id){
        $new_rel_id = $_REQUEST['relate_id'];
        $new_rel_relname = $_REQUEST['relate_to'];
        if(!empty($this->in_workflow) && !empty($this->not_use_rel_in_req)) {
            $new_rel_id = $this->new_rel_id;
            $new_rel_relname = $this->new_rel_relname;
        }
        $new_rel_link = $new_rel_relname;
        //Try to find the link in this bean based on the relationship
        foreach ( $this->field_defs as $key => $def ) {
            if (isset($def['type']) && $def['type'] == 'link'
            && isset($def['relationship']) && $def['relationship'] == $new_rel_relname) {
                $new_rel_link = $key;
            }
        }
        if ($new_rel_link == 'contacts') {
            $accountId = $this->db->getOne('SELECT account_id FROM accounts_contacts WHERE contact_id=' . $this->db->quoted($new_rel_id));
            if ($accountId !== false) {
                if($this->load_relationship('accounts')){
                    $this->accounts->add($accountId);
                }
            }
        }
    }
}
/**
 *
 */
function _get_total_estimated_effort($project_id)
{
    $return_value = '';

    $query = 'SELECT SUM('.$this->db->convert('estimated_effort', "IFNULL", 0).') total_estimated_effort';
    $query.= ' FROM project_task';
    $query.= " WHERE parent_id='{$project_id}' AND deleted=0";

    $result = $this->db->query($query,true," Error filling in additional detail fields: ");
    $row = $this->db->fetchByAssoc($result);
    if($row != null)
    {
        $return_value = $row['total_estimated_effort'];
    }

    return $return_value;
}

/**
 *
 */
function _get_total_actual_effort($project_id)
{
    $return_value = '';

    $query = 'SELECT SUM('.$this->db->convert('actual_effort', "IFNULL", 0).') total_actual_effort';
    $query.=  ' FROM project_task';
    $query.=  " WHERE parent_id='{$project_id}' AND deleted=0";

    $result = $this->db->query($query,true," Error filling in additional detail fields: ");
    $row = $this->db->fetchByAssoc($result);
    if($row != null)
    {
        $return_value = $row['total_actual_effort'];
    }

    return $return_value;
}

/**
 *
 */
function get_summary_text()
{
    return $this->name;
}

/**
 *
 */
function build_generic_where_clause ($the_query_string)
{
    $where_clauses = array();
    $the_query_string = $GLOBALS['db']->quote($the_query_string);
    array_push($where_clauses, "project.name LIKE '%$the_query_string%'");

    $the_where = '';
    foreach($where_clauses as $clause)
    {
        if($the_where != '') $the_where .= " OR ";
        $the_where .= $clause;
    }

    return $the_where;
}

function get_list_view_data()
{
    $field_list = $this->get_list_view_array();
    $field_list['USER_NAME'] = empty($this->user_name) ? '' : $this->user_name;
    $field_list['ASSIGNED_USER_NAME'] = $this->assigned_user_name;
    return $field_list;
}
  function bean_implements($interface){
    switch($interface){
        case 'ACL':return true;
    }
    return false;
}

function create_export_query(&$order_by, &$where, $relate_link_join='')
{
    $custom_join = $this->custom_fields->getJOIN(true, true,$where);
    if($custom_join)
            $custom_join['join'] .= $relate_link_join;
    $query = "SELECT
            project.*,
            users.user_name as assigned_user_name ";
    if($custom_join){
        $query .=  $custom_join['select'];
    }
    $query .= " FROM project ";

    if($custom_join){
        $query .=  $custom_join['join'];
    }
    $query .= " LEFT JOIN users
                ON project.assigned_user_id=users.id ";

    $where_auto = " project.deleted=0 ";

    if($where != "")
        $query .= "where ($where) AND ".$where_auto;
    else
        $query .= "where ".$where_auto;

    if(!empty($order_by)){
        //check to see if order by variable already has table name by looking for dot "."
        $table_defined_already = strpos($order_by, ".");

        if($table_defined_already === false){
            //table not defined yet, define accounts to avoid "ambigous column" SQL error
            $query .= " ORDER BY $order_by";
        }else{
            //table already defined, just add it to end of query
            $query .= " ORDER BY $order_by";
        }
    }
    return $query;
}
function getAllProjectTasks(){
    $projectTasks = array();

    $query = "SELECT * FROM project_task WHERE project_id = '" . $this->id. "' AND deleted = 0 ORDER BY project_task_id";
    $result = $this->db->query($query,true,"Error retrieving project tasks");
    $row = $this->db->fetchByAssoc($result);

    while ($row != null){
        $projectTaskBean = new ProjectTask();
        $projectTaskBean->id = $row['id'];
        $projectTaskBean->retrieve();
        array_push($projectTasks, $projectTaskBean);

        $row = $this->db->fetchByAssoc($result);
    }

    return $projectTasks;
}

} ?>