column($field, $key = '');
返回以$key字段的值作为索引的数组;
$field：要查询的字段，查询所有用 *;
$key: 数据表字段；
举例 :
~~~
public function up(){
$arr = db('Demo')->order('sort asc')->column('*', 'sort');
print_r($arr);
}
~~~
return
~~~
Array
(
[0] => Array
(
[id] => 1
[uid] => 111
[step] => 222
[fraction] => 333
[sort] => 0
[datetime] => 1469764352
)
[2] => Array
(
[id] => 2
[uid] => 3
[step] => 32
[fraction] => 233
[sort] => 2
[datetime] => 1469764352
)
[5] => Array
(
[id] => 3
[uid] => 32
[step] => 332
[fraction] => 2344
[sort] => 5
[datetime] => 1469764352
)
)
~~~
若只填$field , 默认以第一个字段值作为数组索引；
~~~
public function up(){
$arr = db('Demo')->order('sort asc')->column('id,sort,uid');
print_r($arr);
}
~~~
return
~~~
Array
(
[1] => Array
(
[id] => 1
[sort] => 0
[uid] => 111
)
[2] => Array
(
[id] => 2
[sort] => 2
[uid] => 3
)
[3] => Array
(
[id] => 3
[sort] => 5
[uid] => 32
)
)
~~~