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JDBC实现数据库增删改查功能

转载 作者：qq735679552 更新时间：2022-09-29 22:32:09 31 4
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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 。

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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 。

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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 。

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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 。

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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<Course> 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 course = null ;
             list = new ArrayList<Course>();
             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().

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持我.

原文链接：https://blog.csdn.net/weixin_44668898/article/details/107410812 。

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