Thinkphp使用join时多表字段名相同处理

两张数据表
图书表book(id,name,price)
分类表category(id,name)
使用join建立查询

$res = M('book')->field('book.*,category.id as category_id,category.name as category_name')->join('category ON book.cid=category.id')->select();

dump($res);

 打印结果

array(5) {
  [0] => array(6) {
    ["id"] => string(1) "1"
    ["cid"] => string(1) "1"
    ["name"] => string(3) "PHP"
    ["price"] => string(2) "56"
    ["category_id"] => string(1) "1"
    ["category_name"] => string(3) "Web"
  }
  [1] => array(6) {
    ["id"] => string(1) "2"
    ["cid"] => string(1) "1"
    ["name"] => string(10) "Javascript"
    ["price"] => string(2) "45"
    ["category_id"] => string(1) "1"
    ["category_name"] => string(3) "Web"
  }
  [2] => array(6) {
    ["id"] => string(1) "3"
    ["cid"] => string(1) "1"
    ["name"] => string(4) "HTML"
    ["price"] => string(2) "32"
    ["category_id"] => string(1) "1"
    ["category_name"] => string(3) "Web"
  }
  [3] => array(6) {
    ["id"] => string(1) "4"
    ["cid"] => string(1) "2"
    ["name"] => string(5) "MYSQL"
    ["price"] => string(2) "56"
    ["category_id"] => string(1) "2"
    ["category_name"] => string(3) "Sql"
  }
  [4] => array(6) {
    ["id"] => string(1) "5"
    ["cid"] => string(1) "2"
    ["name"] => string(5) "MSSQL"
    ["price"] => string(2) "38"
    ["category_id"] => string(1) "2"
    ["category_name"] => string(3) "Sql"
  }
}