JDBC学习笔记(2)--Staement执行sql语句

1.Staement执行DDL语句

• 创建表

package com.huan.statemennt;

import com.mysql.jdbc.Driver;
import org.junit.Test;

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

/**
 * Created by pc on 17-5-1.
 */
public class StatementDemo {
    String user = "root";
    String password = "root";
    String url = "jdbc:mysql://localhost:3306/eurasia_echarts";
    Connection conn = null;
    Statement state = null;

    @Test
    public void test1() throws Exception {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection(url, user, password);
            if (null != conn) {
                System.out.println("数据库连接成功");
            }
            //创建statement对象
            state = conn.createStatement();
            //创建sql语句
            String sql = " create table mahuan(id int primary key auto_increment ,name varchar(20),age int); ";
            //发送sql语句，执行并返回结果
            int count = state.executeUpdate(sql);
            System.out.println(count);

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            //关闭连接
            if (null != state) {
                state.close();
            }
            if (null != conn) {
                conn.close();
            }
        }
    }
}

2.staement执行执行DML语句

• 插入数据

• 更新数据

• 删除数据

• Dao.java

package com.huan.dao;

import org.junit.Test;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;

/**
 * Created by pc on 17-5-1.
 */
public class Dao {
    static String user ="root";
    static String password = "root";
    static String url = "jdbc:mysql://localhost:3306/eurasia_echarts?characterEncoding=UTF-8";

    @Test
    public static Connection getDao() throws Exception {
        Class.forName("com.mysql.jdbc.Driver");
        Connection conn = DriverManager.getConnection(url, user, password);
        if (null != conn) {
            System.out.println("连接成功");
        }
        return conn;
    }

    public static void close(Statement state, Connection conn){
        if(null != state){
            try {
                state.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(null != conn){
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}

Dml_Demo.java

package com.huan.statemennt;

import com.huan.dao.Dao;
import org.junit.Test;
import java.sql.Connection;
import java.sql.Statement;

/**
 * Created by pc on 17-5-1.
 */
public class Dml_Demo {

    String user ="root";
    String password = "root";
    String url = "jdbc:mysql://localhost:3306/eurasia_echarts?characterEncoding=UTF-8";
    Connection conn = null;
    Statement state = null;
    @Test
    public void test() throws Exception{
        conn =Dao.getDao();
        state = conn.createStatement();
        //插入数据
        String sql = " insert into mahuan (name,age) values('小花',15); ";
        //更新数据
         //String sql = " update mahuan set name ='马欢' where id =3; ";

        //删除数据
        //    String sql = " delete from mahuan where  id = 3; ";

        int count = state.executeUpdate(sql);
        System.out.println(count);

       Dao.close(state,conn);
    }
}

3.staement执行DQL语句

• 查询数据

package com.huan.statemennt;

import com.huan.dao.Dao;
import org.junit.Test;

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

/**
 * Created by pc on 17-5-1.
 */
public class Dql_demo {
    @Test
    public void test() throws Exception {
        Connection conn = null;
        Statement stmt = null;
        conn = Dao.getDao();
        stmt = conn.createStatement();
        String sql = " select * from mahuan; ";

        //接收查询到的所有成绩
        ResultSet rs =stmt.executeQuery(sql);
        while(rs.next()){
            System.out.println("用索引取值：编号："+rs.getInt(1) +" 姓名："+rs.getString(2)+" 年龄："+rs.getString(3));
            System.out.println("用列名称取值：编号："+rs.getInt("id") +" 姓名："+rs.getString("name")+" 年龄："+rs.getString("age"));
        }
        Dao.close(stmt,conn);
    }
}

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