MySQL 获取物理表的主键字段

参考代码：

 1 /**
 2      * 获取主键字段
 3      * @param $table
 4      * @param $database
 5      * @return mixed
 6      */
 7     public function get_primary_key($table,$database){
 8         $sql = "SELECT 
 9             k.column_name
10         FROM 
11             information_schema.table_constraints t
12         JOIN 
13             information_schema.key_column_usage k
14         USING 
15             (constraint_name,table_schema,table_name)
16         WHERE 
17             t.constraint_type='PRIMARY KEY'
18         AND 
19             t.table_schema='$database'
20         AND 
21             t.table_name='$table'";
22         return Db::query($sql)[0]["column_name"];    // 数据库查询语句根据状况而定
23 
24     }