JAVA 连接MSYQL

JDBC连接MYSQL数据库： 

package cn.outofmemory.test;

import java.sql.Connection;
import java.sql.DriverManager;

public class Mysql {
    public static void main(String arg[]) {
        try {
            Connection con = null; //定义一个MYSQL链接对象
            Class.forName("com.mysql.jdbc.Driver").newInstance(); //MYSQL驱动
            con = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/test", "root", "root"); //链接本地MYSQL
            System.out.print("yes");
        } catch (Exception e) {
            System.out.print("MYSQL ERROR:" + e.getMessage());
        }

    }
}

Class.forName("com.mysql.jdbc.Driver").newInstance(); 我们链接的是MYSQL数据库.

所以需要一个MYSQL的数据库驱动，如果你的环境中没有安装， 可以下载：mysql-connector-java-5.1.17-bin.jar JAR包，

然后放进jdk1.6.0_37\jre\lib\ext 重启eclispe 就可以在JRE系统库中看到。

con = DriverManager.getConnection;("jdbc:mysql://127.0.0.1:3306/test", "root", "root"); 是链接数据库的语句， 返回Connection con;对象。

参数格式：("jdbc:mysql://ip:端口/数据库名称", 用户名,密码)

写入一条数据 

package main;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

public class Mysql {

    /**
     * 入口函数
     * @param arg
     */
    public static void main(String arg[]) {
        try {
            Connection con = null; //定义一个MYSQL链接对象
            Class.forName("com.mysql.jdbc.Driver").newInstance(); //MYSQL驱动
            con = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/test", "root", "root"); //链接本地MYSQL

            Statement stmt; //创建声明
            stmt = con.createStatement();

            //新增一条数据
            stmt.executeUpdate("INSERT INTO user (username, password) VALUES ('init', '123456')");
            ResultSet res = stmt.executeQuery("select LAST_INSERT_ID()");
            int ret_id;
            if (res.next()) {
                ret_id = res.getInt(1);
                System.out.print(ret_id);
            }

        } catch (Exception e) {
            System.out.print("MYSQL ERROR:" + e.getMessage());
        }

    }
}

stmt.executeUpdate INSERT; DELETE; UPDATE;语句都用executeUpdate函数来操作 

stmt.executeQuery SELECT;语句都用stmt.executeQuery函数来操作 

ResultSet res = stmt.executeQuery;("select LAST;_INSERT_ID()"); 查询最后插入数据的ID号，返回ResultSet res;对象

删除和更新数据

package main;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

public class Mysql {

    /**
     * 入口函数
     * @param arg
     */
    public static void main(String arg[]) {
        try {
            Connection con = null; //定义一个MYSQL链接对象
            Class.forName("com.mysql.jdbc.Driver").newInstance(); //MYSQL驱动
            con = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/test", "root", "root"); //链接本地MYSQL

            Statement stmt; //创建声明
            stmt = con.createStatement();

            //新增一条数据
            stmt.executeUpdate("INSERT INTO user (username, password) VALUES ('init', '123456')");
            ResultSet res = stmt.executeQuery("select LAST_INSERT_ID()");
            int ret_id;
            if (res.next()) {
                ret_id = res.getInt(1);
                System.out.print(ret_id);
            }

            //删除一条数据
            String sql = "DELETE FROM user WHERE id = 1";
            long deleteRes = stmt.executeUpdate(sql); //如果为0则没有进行删除操作，如果大于0，则记录删除的条数
            System.out.print("DELETE:" + deleteRes);

            //更新一条数据
            String updateSql = "UPDATE user SET username = 'xxxx' WHERE id = 2";
            long updateRes = stmt.executeUpdate(updateSql);
            System.out.print("UPDATE:" + updateRes);

        } catch (Exception e) {
            System.out.print("MYSQL ERROR:" + e.getMessage());
        }

    }
}

删除和更新数据都使用stmt.executeUpdate函数。 

删除和更新数据都会返回一个Long的结果，如果为0，则删除或者更新失败，如果大于0则是操作删除的记录数

查询语句

package main;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;

public class Mysql {

    /**
     * 入口函数
     * @param arg
     */
    public static void main(String arg[]) {
        try {
            Connection con = null; //定义一个MYSQL链接对象
            Class.forName("com.mysql.jdbc.Driver").newInstance(); //MYSQL驱动
            con = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/test", "root", "root"); //链接本地MYSQL

            Statement stmt; //创建声明
            stmt = con.createStatement();

            //新增一条数据
            stmt.executeUpdate("INSERT INTO user (username, password) VALUES ('init', '123456')");
            ResultSet res = stmt.executeQuery("select LAST_INSERT_ID()");
            int ret_id;
            if (res.next()) {
                ret_id = res.getInt(1);
                System.out.print(ret_id);
            }

            //删除一条数据
            String sql = "DELETE FROM user WHERE id = 1";
            long deleteRes = stmt.executeUpdate(sql); //如果为0则没有进行删除操作，如果大于0，则记录删除的条数
            System.out.print("DELETE:" + deleteRes);

            //更新一条数据
            String updateSql = "UPDATE user SET username = 'xxxx' WHERE id = 2";
            long updateRes = stmt.executeUpdate(updateSql);
            System.out.print("UPDATE:" + updateRes);

            //查询数据并输出
            String selectSql = "SELECT * FROM user";
            ResultSet selectRes = stmt.executeQuery(selectSql);
            while (selectRes.next()) { //循环输出结果集
                String username = selectRes.getString("username");
                String password = selectRes.getString("password");
                System.out.print("\r\n\r\n");
                System.out.print("username:" + username + "password:" + password);
            }

        } catch (Exception e) {
            System.out.print("MYSQL ERROR:" + e.getMessage());
        }

    }
}

查询语句使用stmt.executeQuery函数

• rs.absolute() //绝对位置，负数表示从后面数
• rs.first()第一条
• rs.last()最后一条
• rs.previoust()前一条
• rs.next()后一条
• rs.beforeFirst()第一条之前
• rs.afterLast()最后之后
• rs.isFirst(),rs.isLast(),rs.isBeforeFirst(),rs.isAfterLast