java操作mysql的增删改查_java web jsp连接mysql增删改查语句hashmap-优快云博客

本文提供了一个使用Java连接MySQL数据库的示例代码，包括连接、插入、更新、删除及查询等基本操作，并详细展示了如何处理异常。

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其中，需要把mysql与java连接的jar（mysql-connector-java-5.1.6-bin.jar）包导入工程.

package com.cn.edu; import java.beans.Statement; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; public class helloworld { private Connection conn = null; PreparedStatement statement = null; // connect to MySQL void connSQL() { String url = "jdbc:mysql://localhost:3306/hello?characterEncoding=UTF-8"; String username = "root"; String password = "root"; // 加载驱动程序以连接数据库 try { Class.forName("com.mysql.jdbc.Driver" ); conn = DriverManager.getConnection( url,username, password ); } //捕获加载驱动程序异常 catch ( ClassNotFoundException cnfex ) { System.err.println( "装载 JDBC/ODBC 驱动程序失败。" ); cnfex.printStackTrace(); } //捕获连接数据库异常 catch ( SQLException sqlex ) { System.err.println( "无法连接数据库" ); sqlex.printStackTrace(); } } // disconnect to MySQL void deconnSQL() { try { if (conn != null) conn.close(); } catch (Exception e) { System.out.println("关闭数据库问题："); e.printStackTrace(); } } // execute selection language ResultSet selectSQL(String sql) { ResultSet rs = null; try { statement = conn.prepareStatement(sql); rs = statement.executeQuery(sql); } catch (SQLException e) { e.printStackTrace(); } return rs; } // execute insertion language boolean insertSQL(String sql) { try { statement = conn.prepareStatement(sql); statement.executeUpdate(); return true; } catch (SQLException e) { System.out.println("插入数据库时出错："); e.printStackTrace(); } catch (Exception e) { System.out.println("插入时出错："); e.printStackTrace(); } return false; } //execute delete language boolean deleteSQL(String sql) { try { statement = conn.prepareStatement(sql); statement.executeUpdate(); return true; } catch (SQLException e) { System.out.println("插入数据库时出错："); e.printStackTrace(); } catch (Exception e) { System.out.println("插入时出错："); e.printStackTrace(); } return false; } //execute update language boolean updateSQL(String sql) { try { statement = conn.prepareStatement(sql); statement.executeUpdate(); return true; } catch (SQLException e) { System.out.println("插入数据库时出错："); e.printStackTrace(); } catch (Exception e) { System.out.println("插入时出错："); e.printStackTrace(); } return false; } // show data in ju_users void layoutStyle2(ResultSet rs) { System.out.println("-----------------"); System.out.println("执行结果如下所示:"); System.out.println("-----------------"); System.out.println(" 用户ID" + "/t/t" + "淘宝ID" + "/t/t" + "用户名"+ "/t/t" + "密码"); System.out.println("-----------------"); try { while (rs.next()) { System.out.println(rs.getInt("ju_userID") + "/t/t" + rs.getString("taobaoID") + "/t/t" + rs.getString("ju_userName") + "/t/t"+ rs.getString("ju_userPWD")); } } catch (SQLException e) { System.out.println("显示时数据库出错。"); e.printStackTrace(); } catch (Exception e) { System.out.println("显示出错。"); e.printStackTrace(); } } public static void main(String args[]) { helloworld h = new helloworld(); h.connSQL(); String s = "select * from ju_users"; String insert = "insert into ju_users(ju_userID,TaobaoID,ju_userName,ju_userPWD) values("+8329+","+34243+",'mm','789')"; String update = "update ju_users set ju_userPWD =123 where ju_userName= 'mm'"; String delete = "delete from ju_users where ju_userName= 'mm'"; if (h.insertSQL(insert) == true) { System.out.println("insert successfully"); ResultSet resultSet = h.selectSQL(s); h.layoutStyle2(resultSet); } if (h.updateSQL(update) == true) { System.out.println("update successfully"); ResultSet resultSet = h.selectSQL(s); h.layoutStyle2(resultSet); } if (h.insertSQL(delete) == true) { System.out.println("delete successfully"); ResultSet resultSet = h.selectSQL(s); h.layoutStyle2(resultSet); } h.deconnSQL(); } }

notice:

1、现在一般用的驱动是com.mysql.jdbc.Driver，以前的那个什么org的驱动虽然封装了com.mysql.jdbc.Driver，但不好用，过时了。

2、prepareStatement(sql)是statement的子类，比statement好用。

3、如果数据库中定义的是int值，那么sql语句中要把int单独提出来。如".....values("+8329+","+34243+",'mm','789')"