Jdbc--实现对数据库的查询，更改，删除，添加等方法

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','tom@163.com'),
('2','jack','456','jack@163.com');

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','liuye@163.com')";
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='bwt149@163.com' 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();
}

}

}*/

}