JDBC练习_select语句

定义一个方法，查询emp表的数据将其封装为对象，返回

　　定义emp;类编写对应字段。

　　定义方法 public List <Emp> find(){ }

　　实现方法 select * from emp;

 

java代码实例：

　　　　

@Data
@NoArgsConstructor
@AllArgsConstructor
public class Emp {

    private int id;
    private String ename;
    private int job_id;
    private int mgr;
    private Date joindate;
    private double salary;
    private double bounds;
    private int dept_id;

}

 

public static void main(String[] args) {

        List<Emp> all = new jdbcdemo08().findAll();
        System.out.println(all);
        System.out.println(all.size());
    }

    public List<Emp> findAll(){
        List<Emp> list = null;
        Connection connection = null;
        ResultSet resultSet = null;
        Statement statement = null;
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            connection = DriverManager.getConnection("jdbc:mysql:///a2", "root", "root");
            String sql = "select * from emp";
            statement = connection.createStatement();
            resultSet = statement.executeQuery(sql);
            Emp emp = null;
            list = new ArrayList<>();

            while (resultSet.next()){
                int id = resultSet.getInt("id");
                String ename = resultSet.getString("ename");
                int job_id = resultSet.getInt("job_id");
                int mgr = resultSet.getInt("mgr");
                Date joindate = resultSet.getDate("joindate");
                double salary = resultSet.getDouble("salary");
                double bonus = resultSet.getDouble("bonus");
                int dept_id = resultSet.getInt("dept_id");

                emp = new Emp();
                emp.setId(id);
                emp.setEname(ename);
                emp.setJob_id(job_id);
                emp.setMgr(mgr);
                emp.setJoindate(joindate);
                emp.setSalary(salary);
                emp.setBounds(bonus);
                emp.setDept_id(dept_id);

                list.add(emp);
            }
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }catch (SQLException e){
            e.printStackTrace();
        }finally {
            if (resultSet !=null){
                try {
                    resultSet.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
            if (statement !=null){
                try {
                    statement.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
            if (connection !=null){
                try {
                    connection.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
        }
        return list;
    }

 

 

 

 

搜索

　　

 

复制