mysql获取自增长id

前提是这个表的id设置为了自增长,在Mysql创建表的时候，AUTO_INCREMENT就表示自增长

CREATE TABLE user (

  id int(11) AUTO_INCREMENT,

  name varchar(30) ,

  password varchar(30),

  PRIMARY KEY (id)

) ;

insert into user values(null,'dashen','thisispassword');

package test;

import java.sql.*;

public class add
{
    public static void main(String[] args) {
        //先导入jar包mysql-connector-java-5.1.39-bin.jar
        //初始化驱动
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        String sql="INSERT INTO user VALUES (null,?,?)";
        //使用try-with-resource的方式自动关闭连接
        try (
                //建立数据库链接
                Connection c= DriverManager.getConnection("jdbc:mysql://localhost:3306/how2java?characterEncoding=utf-8",
                "root","123456");
                //创建语句
                PreparedStatement ps=c.prepareStatement(sql, Statement.RETURN_GENERATED_KEYS);
        ){
            ps.setString(1,"ee");
            ps.setString(2,"ff");
            ps.execute();
            // 在执行完插入语句后，MySQL会为新插入的数据分配一个自增长id
            // JDBC通过getGeneratedKeys获取该id
            ResultSet rs = ps.getGeneratedKeys();
            if (rs.next()) {
                int id = rs.getInt(1);
                System.out.println(id);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}