```sql
DataTable dt = new DBHelper().GetDataTable1("select * from zc_card card left join v_zc_info zc on zc.guid=card.zc_guid where card.id=@id", new SqlParameter[] { new SqlParameter("@id", id) });
```
select * from zc_card card
left join v_zc_info zc on zc.guid=card.zc_guid where card.id=@id
这句sql是主表根据id查询数据,左连接子表
注意,一般写on后面是主表id=子表id
根据卡号查询卡片信息
内联查询 2楼正解