codeigniter和mysql更新错误？

when i try to update a table i get an error that time.

there is my controller code.

$this->hr_user->insert_user($info);

        $n=explode('--', $info['user_code']);
        $temp=$n[1];
        $lnum=ltrim($temp,'0');
        //print_r($lnum);
        //echo "<br>lastnumber".$lnum;
        $id=$info['user_type'];
        echo $id.''.$lnum;



        $this->hr_user->update_number($id,$lnum);



        redirect('hrm/index');

and here is my model code.

public function update_number($id,$lnum)
{
    $this->db->where('em_id',$id);
    $this->db->update('tbl_emaster.em_lastnumber',$lnum);

}

The mysql error you got explains every thing. Your query order doesn't generate a qualified query, try:

public function update_number($id,$lnum)
{
    $this->db->set('eenter code herem_lastnumber', '$lnum');
    $this->db->where('em_id',$id);
    $this->db->update('emaster');
}

for more info www.codeigniter.com

Mysql update query syntax is :

UPDATE table_name SET field1 = new-value1, field2 = new-value2
[WHERE Clause]

You can see, there are fields after SET. And because of your CI update syntax, column name is not being passed. And to pass that, you should pass array as 2nd argument of $this->db->update('tbl_emaster.em_lastnumber',$lnum);

So you need to change it like this:

$this->db->update('tbl_emaster',array('em_lastnumber' => $lnum);

$this->db->set('field', 'field+1');
$this->db->where('id', 2);
$this->db->update('mytable'); 
// gives UPDATE `mytable` SET `field` = '   field+1' WHERE `id` = 2

https://www.codeigniter.com/userguide3/database/query_builder.html#updating-data

change query

public function update_number($id,$lnum)
{
    $data=array('em_lastnumber'=>$lnum);
    $this->db->where('em_id',$id);
    $this->db->update('tbl_emaster',$data);

}