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服务器之家。
原文链接：https://blog.csdn.net/weixin_44668898/article/details/107410812
