JDBC实现数据库增删改查功能

JDBC实现数据库增删改查功能

JDBC，简单点来说，就是用java操作数据库，下面简单介绍怎么实现数据库的增删改查功能。

1、添加数据

package cn.itcast.jdbc;

import java.sql.*;

public class JdbcDemo2 {

public static void main(String[] args) {

Connection connection = null;

PreparedStatement preparedStatement = null;

try {

//1、注册驱动

Class.forName("com.mysql.jdbc.Driver");

//2、定义sql

String sql = "insert into course values(?,?,?)";

//3、获取Connection对象

//student表示你要操作的数据库

//如果是locakhost：3306，也可以简写为"jdbc:mysql:///student"

connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/student","root","root");

//4、获取执行sql的对象

preparedStatement = connection.prepareStatement(sql);

//传入参数

preparedStatement.setInt(1,5);

preparedStatement.setString(2,"JavaWeb");

preparedStatement.setInt(3,88);

//5、执行sql

int count = preparedStatement.executeUpdate();

//6、处理结果

System.out.println(count);

if (count > 0) {

System.out.println("添加成功");

} else {

System.out.println("添加失败");

}

} catch (ClassNotFoundException e) {

e.printStackTrace();

} catch (SQLException e) {

e.printStackTrace();

} finally {

//7、释放资源

//避免空指针异常

if (preparedStatement != null) {

try {

preparedStatement.close();

} catch (SQLException e) {

e.printStackTrace();

}

}

if (connection != null) {

try {

connection.close();

} catch (SQLException e) {

e.printStackTrace();

}

}

}

}

}

2、删除数据

package cn.itcast.jdbc;

import java.sql.*;

public class JdbcDemo4 {

public static void main(String[] args) {

Connection connection = null;

PreparedStatement preparedStatement = null;

try {

//1、注册驱动

Class.forName("com.mysql.jdbc.Driver");

//2、获取连接对象

connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/student","root","root");

//3、定义sql

String sql = "delete from course where cno = ?";

//4、获取执行sql对象

preparedStatement = connection.prepareStatement(sql);

preparedStatement.setInt(1,5);

//5、执行sql

int count = preparedStatement.executeUpdate();

//6、处理结果

System.out.println(count);

if (count > 0) {

System.out.println("删除成功");

} else {

System.out.println("删除失败");

}

} catch (ClassNotFoundException e) {

e.printStackTrace();

} catch (SQLException e) {

e.printStackTrace();

} finally {

//7、释放资源

if (preparedStatement != null) {

try {

preparedStatement.close();

} catch (SQLException e) {

e.printStackTrace();

}

}

if (connection != null) {

try {

connection.close();

} catch (SQLException e) {

e.printStackTrace();

}

}

}

}

}

3、修改数据

package cn.itcast.jdbc;

import java.sql.*;

public class JdbcDemo3 {

public static void main(String[] args) {

Connection connection = null;

PreparedStatement preparedStatement = null;

try {

//1、注册驱动

Class.forName("com.mysql.jdbc.Driver");

//2、获取连接对象

connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/student", "root", "root");

//3、定义sql

String sql = "update course set period = ? where cno = ?";

//4、获取执行sql对象

preparedStatement = connection.prepareStatement(sql);

//设置参数

preparedStatement.setInt(1,90);

preparedStatement.setInt(2,1);

//5、执行sql

int count = preparedStatement.executeUpdate();

//6、处理结果

System.out.println(count);

if (count > 0) {

System.out.println("修改成功！");

} else {

System.out.println("修改失败！");

}

} catch (ClassNotFoundException e) {

e.printStackTrace();

} catch (SQLException e) {

e.printStackTrace();

} finally {

//7、释放资源

if (preparedStatement != null) {

try {

preparedStatement.close();

} catch (SQLException e) {

e.printStackTrace();

}

}

if (connection != null) {

try {

connection.close();

} catch (SQLException e) {

e.printStackTrace();

}

}

}

}

}

4、查询数据

package cn.itcast.jdbc;

import cn.itcast.domain.Course;

import java.sql.*;

import java.util.ArrayList;

import java.util.List;

public class JDBCDemo5 {

/**

* 查询所有Course对象

* @return

*/

public static void main(String[] args) {

Connection connection = null;

PreparedStatement preparedStatement = null;

ResultSet resultSet = null;

List list = null;

try {

//1、注册驱动

Class.forName("com.mysql.jdbc.Driver");

//2、获取连接

connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/student", "root", "root");

//3、定义sql

String sql = "select * from course";

//4、获取执行sql的对象

preparedStatement = connection.prepareStatement(sql);

//5、执行sql

resultSet = preparedStatement.executeQuery();

//6、遍历结果集，封装对象，装载集合

Course http://course = null;

list = new ArrayList();

while (resultSet.next()) {

//获取数据

int cno = resultSet.getInt("cno");

String cname = resultSet.getString("cname");

int period = resultSet.getInt("period");

//创建Course对象并赋值

course = new Course();

course.setCno(cno);

course.setCname(cname);

course.setPeriod(period);

//装载集合

list.add(course);

}

} catch (ClassNotFoundException e) {

e.printStackTrace();

} catch (SQLException e) {

e.printStackTrace();

} finally {

if (resultSet != null) {

try {

resultSet.close();

} catch (SQLException e) {

e.printStackTrace();

}

}

if (preparedStatement != null) {

try {

preparedStatement.close();

} catch (SQLException e) {

e.printStackTrace();

}

}

if (connection != null) {

try {

connection.close();

} catch (SQLException e) {

e.printStackTrace();

}

}

}

System.out.println(list);

}

}

我们可以发现，增删改的操作基本都是差不多的语句，且执行sql的语句都是一样的，都是preparedStatement.executeUpdate()。但查询操作就有所不同了，返回的是一个结果集，且执行sql的语句就是preparedStatement.executeQuery()。

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