jdbc笔记(一) 使用Statement对单表的CRUD操作

jdbc连接mysql并执行简单的CRUD的步骤：

1.注册驱动（需要抛出/捕获异常）

Class.forName("com.mysql.jdbc.Driver");

2.建立连接需要抛出/捕获异常）

connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/testdb", "root", "Danny2036");

3.创建statement

statement = connection.createStatement();

4.创建sql语句

String sql = "insert into user values(10, \"noname\", 31)";

5.执行sql语句，如果是查询需要用ResultSet接收结果集

int affectrows = statement.executeUpdate(sql);
System.out.println(affectrows);

6.关闭资源

if (statement != null) {
    statement.close();
}
if (connection != null) {
    connection.close();
}

————————————————————————分割线——————————————————————————————————

最后贴出全部代码（包括insert，selectOne和selectAll）

package com.colin.dao;

import java.sql.*;

public class JdbcTest {

    /**
     * 插入语句
     * @param id 主键id int
     * @param name 姓名 String
     * @param age 年龄 int
     */
    public static void update(int id, String name, int age) throws SQLException {
        long starttime = System.currentTimeMillis();

        Connection connection = null;
        Statement statement = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            connection = DriverManager.getConnection(
                    "jdbc:mysql://localhost:3306/testdb",
                    "root", "Danny2036");
            statement = connection.createStatement();
            String sql = "update user set name = \'" + name + "\', age = "+ age +" where id = " + id;
            System.out.println(sql);
            int affectrows = statement.executeUpdate(sql);
            System.out.println(affectrows);

        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            if (connection != null) {
                connection.close();
            }
            if (statement != null) {
                statement.close();
            }
        }

        System.out.println(System.currentTimeMillis() - starttime);

    }

    public static void selectOne(int id) throws ClassNotFoundException, SQLException {

        Statement statement = null;
        Connection connection = null;

        try {
            // 注册驱动
            Class.forName("com.mysql.jdbc.Driver");
            // 建立连接
            connection = DriverManager.getConnection(
                    "jdbc:mysql://localhost:3306/testdb",
                    "root", "Danny2036"
            );
            // 创建statement
            statement = connection.createStatement();
            // 定义sql语句
            String sql = "SELECT id, name, age FROM user where id = " + id;
            // 执行sql语句并获得结果
            ResultSet resultSet = statement.executeQuery(sql);
            // 遍历结果集
            while (resultSet.next()) {
                int idResult = (int) resultSet.getInt("id");
                String nameResult = (String) resultSet.getString("name");
                int ageResult = (int) resultSet.getInt("age");

                System.out.println(idResult + "\t" + nameResult + "\t" + ageResult);
            }
        } finally {
            if (statement != null) {
                statement.close();
            }
            if (connection != null) {
                connection.close();
            }
        }

    }

    public static void selectAll() throws ClassNotFoundException, SQLException {

        Statement statement = null;
        Connection connection = null;

        try {
            // 注册驱动
            Class.forName("com.mysql.jdbc.Driver");
            // 建立连接
            connection = DriverManager.getConnection(
                    "jdbc:mysql://localhost:3306/testdb",
                    "root", "Danny2036"
            );
            // 创建statement
            statement = connection.createStatement();
            // 定义sql语句
            String sql = "SELECT id, name, age FROM user";
            // 执行sql语句并获得结果
            ResultSet resultSet = statement.executeQuery(sql);
            // 遍历结果集
            while (resultSet.next()) {
                int idResult = (int) resultSet.getInt("id");
                String nameResult = (String) resultSet.getString("name");
                int ageResult = (int) resultSet.getInt("age");

                System.out.println(idResult + "\t" + nameResult + "\t" + ageResult);
            }
        } finally {
            if (statement != null) {
                statement.close();
            }
            if (connection != null) {
                connection.close();
            }
        }

    }

    public static void main(String[] args) throws SQLException, ClassNotFoundException {
        selectAll();
    }

/*

    // 向上抛异常的方式
    public static void main(String[] args)
            throws ClassNotFoundException, SQLException {

        long starttime = System.currentTimeMillis();

        Connection connection = null;
        Statement statement = null;

        try {
            //注册驱动
            Class.forName("com.mysql.jdbc.Driver");
            //建立连接
            connection = DriverManager.getConnection(
                    "jdbc:mysql://localhost:3306/testdb",
                    "root", "Danny2036");
            //创建statement
            statement = connection.createStatement();
            //定义sql
            String sql = "insert into user values(10, \"noname\", 31)";
            //执行sql，如果是查询需返回结果集
            int affectrows = statement.executeUpdate(sql);
            System.out.println(affectrows);

        } finally {

            //关闭资源
            if (statement != null) {
                statement.close();
            }
            if (connection != null) {
                connection.close();
            }

        }

        System.out.println("总执行时间： " + (System.currentTimeMillis() - starttime));

    }
*/

/*

    // 捕获异常的方式
    public static void main(String[] args) throws SQLException {

        long starttime = System.currentTimeMillis();

        Statement statement = null;
        Connection connection = null;
        try {
            // 注册驱动
            Class.forName("com.mysql.jdbc.Driver");
            // 建立连接
            connection = DriverManager.getConnection(
                    "jdbc:mysql://localhost:3306/testdb?useSSL=true",
                    "root", "Danny2036");
            // 创建statement
            statement = connection.createStatement();
            // 定义sql
            String sql = "insert into user values(9, \"ahaha\", 22)";
            // 执行sql，如果是查询，遍历结果集
            int affectrows = statement.executeUpdate(sql);
            System.out.println(affectrows);

        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {

            // 关闭资源
            if (statement != null) {
                statement.close();
            }
            if (connection != null) {
                connection.close();
            }

        }

        System.out.println("总用时 ： " + (System.currentTimeMillis() - starttime));

    }
*/

}

——————————————————**********最后附上bean代码***********————————————————————

package com.colin.bean;

public class User {

    private int id;
    private String name;
    private int age;

    public User(int id, String name, int age) {
        this.id = id;
        this.name = name;
        this.age = age;
    }

    public User(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}