mysql查询在数据库正常，但是在java里就报错

Question

select i.id,i.price,i.amount,g.name from orderitem i ,goods g where order_id = ? and i.goods_id = g.id
java.sql.SQLException: Cannot create com.yanzi.model.OrderItem: com.yanzi.model.OrderItem Query: select i.id,i.price,i.amount,g.name from orderitem i ,goods g where order_id = ? and i.goods_id = g.id Parameters: [9]

---

public List<OrderItem> selectAllItem(int orderid) throws SQLException {
    QueryRunner r = new QueryRunner(DBUtil.getDataSource());        
    String sql = "select i.id,i.price,i.amount,g.name from orderitem i ,goods g where order_id = ? and i.goods_id = g.id";
    System.out.println(sql);
    return r.query(sql, new BeanListHandler<OrderItem>(OrderItem.class),orderid);
}

Answer 1

先这样写

public List<Map< String, Object>> selectAllItem(int orderid) throws SQLException {
QueryRunner r = new QueryRunner(DBUtil.getDataSource());

String sql = "select i.id,i.price,i.amount,g.name from orderitem i ,goods g where order_id = ? and i.goods_id = g.id";
System.out.println(sql);
return r.query(sql, new MapListHandler(),orderid);
}
看报不报错，没错的话sql没问题；
接下来检查 OrderItem 有没public 无参构造方法，字段名与SQL 列的对应关系。

参考demo： https://gitee.com/00fly/java-code-frame/tree/master/dbutils-jdbc