(笔记) 在JDBC中用JAVA查询单条记录
public static Department getById(int department_id){
Connection con=DMmanager.getConnection();
PreparedStatement pst= null;
String str="select * from department where department_id =?";
pst=con.prepareStatement(str);
(1)因为此处有一展位符,所以???? pst.setInt(1,department_id);
ResultSet rs=null;
rs = pst.executeQuery();
while(rs.hasNext){
Department dep = new Department();
dep.setId(rs.getInt("department_id"));
dep.setName(rs.getString("department_name"));
dep.setSalary(rs.getFloat("salary"));
dep.setLocation_id(rs.getInt("location_id"));
}
rs.close();
pst.close();
con.close();
return dep;
}
与查询department所有数据相比,为什么在简单数据查询时会要有(1)在了,其作用是什么?
ps:此代码有出入.....只用于做解构式模块分析