特别这个SQL
public function SearchEmploye($key, $index, $size, $sortField, $sortOrder){
$myconn = createDB();
$sql = "
select a.*, b.name dept_name, c.name position_name, d.name educational_name
from t_employee a
left join t_department b
on a.dept_id = b.id
left join t_position c
on a.position = c.id
left join t_educational d
on a.educational = d.id
where a.name like '%" . $key . "%'";
if(!empty($sortField)){
if ($sortOrder != "desc") $sortOrder = "asc";
$sql .= " order by " . $sortField . " " . $sortOrder;
}else{
$sql .= " order by createtime desc";
}