Jdbc--实现对数据库的查询，更改，删除，添加等方法

1.先新建一个数据库，代码如下：

CREATE TABLE user_t (
    id INT(11) UNSIGNED NOT NULL AUTO_INCREMENT,
    name VARCHAR(50) NOT NULL DEFAULT '',
    password VARCHAR(50) NOT NULL DEFAULT '',
    email VARCHAR(50) NOT NULL DEFAULT '',
    PRIMARY KEY (id)
)  ENGINE=INNODB DEFAULT CHARSET=UTF8;

insert into user_t (id,name,password,email) values
('1','tom','123','[email protected]'),
('2','jack','456','[email protected]');

2.java代码如下：

package JdbcPrictice;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.text.Normalizer.Form;

import javax.swing.text.DefaultEditorKit.InsertBreakAction;

import jdk.nashorn.internal.ir.ForNode;


public class MyJdbc {
	
	//方法getConnection（） 获取与数据库连接	
	public static Connection getConnection()
	{
		Connection con=null;		
		try {
			Class.forName("com.mysql.jdbc.Driver");
			con=DriverManager.getConnection("jdbc:mysql://localhost:3306/new_Prictice","root","");
	
		} catch (Exception e) {
		   e.printStackTrace();
		   
		}
		return con;		
	}
	//往数据库中添加数据的方法
	public void insert()
	{
		Connection con=this.getConnection();
		try {
			String  sql="insert into user_t (id,name,password,email) values "
					+ "('3','liuye','admin','[email protected]')";
			Statement st=con.createStatement();
			int count =st.executeUpdate(sql);
			System.out.println("数据库添加了"+count+"条记录");

		} catch (Exception e) {
			e.printStackTrace();
		}
		
	}
	
	//更新数据库已有记录的方法
	public void update(){
		Connection con = this.getConnection();
		try {
			String sql ="update user_t set email='[email protected]' where name='tom'";
			Statement st=con.createStatement();
			int count=st.executeUpdate(sql);
			System.out.println("想数据库更新了"+count +"条记录");			
		} catch (Exception e) {
			e.printStackTrace();
		}				
	}
	
	//删除已有记录的方法
	public void  delete(){
		Connection con=this.getConnection();
		try {
			//将sql代码包装到字符串
			String sql="delete from user_t where name='tom'";
			Statement st=con.createStatement();			
			// 调用execute方法执行sql语句      st.execute(sql);
			//此方法可以再执行sql的同时获取更改的次数
			int count =st.executeUpdate(sql);
	
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	
	
	//执行已有的数据库操作方法
	public static void main(String[] args) {
		
		MyJdbc my= new  MyJdbc();
		//my.insert();
		//my.update();
		my.delete();
		
	}
	
	
	/*
	 此main（）方法为查询数据库的方法
	public static void main(String[] args) {
		
		String  sql="Select*from user_t";		
		Connection con=null;
		Statement st=null;
		ResultSet rs=null;		
		try {
			
			Class.forName("com.mysql.jdbc.Driver");
			System.out.println("数据库驱动加载成功");
			
			con=DriverManager.getConnection("jdbc:mysql://localhost:3306/new_prictice","root","");
			System.out.println("数据库连接成功");
			st=con.createStatement();
			
			rs=st.executeQuery(sql);
			
			while(rs.next()){
				
				System.out.print(rs.getInt("id")+"   ");
				System.out.print(rs.getString("name")+"  ");
				System.out.print(rs.getString("password")+"  ");
				System.out.print(rs.getString("email")+"   ");
				System.out.println();
				
			}
			
		} catch (Exception e) {
			
			e.printStackTrace();
			
		}finally{
			
			try {
				rs.close();
				
			} catch (Exception e2) {
				e2.printStackTrace();
			}
			try {
				st.close();
				
			} catch (Exception e2) {
				e2.printStackTrace();
			}
			try {
				con.close();
				
			} catch (Exception e2) {
				e2.printStackTrace();
			}
		
		}
	
	}*/

}