package com.litian.jdbc;

import javax.swing.plaf.nimbus.State;

import java.sql.*;

/**

 * @author: Li Tian

 * @contact: litian_cup@163.com

 * @software: IntelliJ IDEA

 * @file: JDBCTest3.java

 * @time: 2020/3/29 15:27

 * @desc: |取得数据库自动生成的主键值

 */

public class JDBCTest3 {

    public static void main(String[] args){

        Connection conn = null;

        PreparedStatement ps = null;

        try {

            conn = JDBCTools.getConnection();

            String sql = "insert into t_user(username, pwd) values(?,?)";

            // ps = conn.prepareStatement(sql);

            // 使用重载的ps方法来生成ps对象

            ps = conn.prepareStatement(sql, Statement.RETURN_GENERATED_KEYS);

            ps.setString(1, "pika");

            ps.setString(2, "123456");

            ps.executeUpdate();

            // 通过getGeneratedKeys方法获取包含了新生成的主键的ResultSet对象

            // 在ResultSet中只有一列GENERATED_KEYS，用于存放新生成的主键值

            ResultSet rs = ps.getGeneratedKeys();

            if(rs.next()){

                System.out.println(rs.getInt(1));

            }

            ResultSetMetaData rsmd = rs.getMetaData();

            for (int i = 0; i < rsmd.getColumnCount(); i++) {

                System.out.println(rsmd.getColumnName(i + 1));

            }

        } catch (Exception e) {

            e.printStackTrace();

        } finally {

            JDBCTools.release(null, ps, conn);

        }

    }

}