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
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 |
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
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 |
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
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 |
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
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 |
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。
原文链接：https://blog.csdn.net/weixin_44668898/article/details/107410812