zoukankan      html  css  js  c++  java
  • JDBC使用过程

    导入包:

    import java.sql.*;

    注册JDBC驱动程序:

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

    打开一个连接:

    conn = DriverManager.getConnection(DB_URL,USER,PASS);

    执行一个查询

    stmt = conn.createStatement();

    String sql;

    sql = "SELECT id, first, last, age FROM Employees";

    ResultSet rs = stmt.executeQuery(sql);

    sql = "DELETE FROM Employees";

    ResultSet rs = stmt.executeUpdate(sql);

    从结果集中提取数据:

    while(rs.next()){

        //Retrieve by column name

        int id  = rs.getInt("id");

        int age = rs.getInt("age");

        String first = rs.getString("first");

        String last = rs.getString("last");

            

    清理环境:    

    rs.close();

    stmt.close();

    conn.close();

    //STEP 1. Import required packages

    import java.sql.*;

    public class FirstExample {

       // JDBC driver name and database URL

       static final String JDBC_DRIVER = "com.mysql.jdbc.Driver"; 

       static final String DB_URL = "jdbc:mysql://localhost/EMP";

       //  Database credentials

       static final String USER = "username";

       static final String PASS = "password";

      

       public static void main(String[] args) {

       Connection conn = null;

       Statement stmt = null;

       try{

          //STEP 2: Register JDBC driver

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

          //STEP 3: Open a connection

          System.out.println("Connecting to database...");

          conn = DriverManager.getConnection(DB_URL,USER,PASS);

          //STEP 4: Execute a query

          System.out.println("Creating statement...");

          stmt = conn.createStatement();

          String sql;

          sql = "SELECT id, first, last, age FROM Employees";

          ResultSet rs = stmt.executeQuery(sql);

          //STEP 5: Extract data from result set

          while(rs.next()){

             //Retrieve by column name

             int id  = rs.getInt("id");

             int age = rs.getInt("age");

             String first = rs.getString("first");

             String last = rs.getString("last");

             //Display values

             System.out.print("ID: " + id);

             System.out.print(", Age: " + age);

             System.out.print(", First: " + first);

             System.out.println(", Last: " + last);

          }

          //STEP 6: Clean-up environment

          rs.close();

          stmt.close();

          conn.close();

       }catch(SQLException se){

          //Handle errors for JDBC

          se.printStackTrace();

       }catch(Exception e){

          //Handle errors for Class.forName

          e.printStackTrace();

       }finally{

          //finally block used to close resources

          try{

             if(stmt!=null)

                stmt.close();

          }catch(SQLException se2){

          }// nothing we can do

          try{

             if(conn!=null)

                conn.close();

          }catch(SQLException se){

             se.printStackTrace();

          }//end finally try

       }//end try

       System.out.println("Goodbye!");

    }//end main

    }//end FirstExample - by www.yiibai.com

  • 相关阅读:
    node express 上传文件
    [Java] 对象转型-01
    [Java] 类的Equals方法 (String, Data类都已经自动重写)
    editor does not contain a main type" 错误解决方
    Ubuntu网络连接图标消失解决方法
    [面试] 从尾到头打印链表-递归实现
    C++继承的例子 (1)
    国内访问gmail
    [python] 第7章 函数 第8章 模块
    Devcpp(Dev C++)使用说明及技巧
  • 原文地址:https://www.cnblogs.com/corolliberty/p/5980961.html
Copyright © 2011-2022 走看看