### min
获得某个列中的最小的值
min($table, $column, $where)
* ##### table [string]
表名.
* ##### column [string]
需要查询的列.
* ##### where (optional) [array]
WHERE 条件.
min($table, $join, $column, $where)
* ##### table [string]
The table name.
* ##### join [array]
Table relativity for table joining.
* ##### column [string]
The target column will be calculated.
* ##### where (optional) [array]
The WHERE clause to filter records.
Return: [number] 返回最小的值.
~~~
$min = $database->min("account", "age", [
"gender" => "male"
]);
echo "The age of youngest male user is " . $min;
~~~
