模型的小改动：

function loadsuppliers()
{       
    $this->db->select('SupplierID, Name');
    $records=$this->db->get('supplier');
    $data=array();
    if($records->num_rows() > 0){
        $data   = $records->result_array();
    }
    return ($data);
}

在你看来SupplierMGT.php，这样写：

<select name="" id="" multiple="">
    <?php
        if(isset($unit) && is_array($unit) && count($unit) > 0){
            foreach($unit as $key=>$each){

    ?>
    <option value="<?=$each['SupplierID']?>"><?=$each['Name']?></option>
    <?php
            }
        }
    ?>
</select>