Java JDBC 查询数据

• 

  查询数据

  考虑我们有下面一个MySQL表：

  CREATE TABLE `tutorials_tbl` (
    `tutorial_id` int(11) NOT NULL AUTO_INCREMENT,
    `tutorial_title` varchar(100) COLLATE utf8mb4_unicode_ci NOT NULL,
    `tutorial_author` varchar(40) COLLATE utf8mb4_unicode_ci NOT NULL,
    `submission_date` date DEFAULT NULL,
    PRIMARY KEY (`tutorial_id`)
  ) ENGINE=InnoDB CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci

  表里面有三条数据：

  

  提示:不熟悉MySQL的同学可以到我们的MySQL教程进行学习。

  下面展示获取这三条条数据并展示的例子：

  import java.sql.*;
   
  
  public class MyClass {
          //驱动字符串
          final static String driverStr="com.mysql.cj.jdbc.Driver";
          final static String dbHost = "192.168.61.125";  // 主机  可为ip地址
          final static String dbUserName = "root";  // 用户
          final static String dbPassword = "123456"; // 密码
          final static String dbPort = "3306"; // 端口
          final static String dbName = "mydb"; // 数据库名
          final static String connStr="jdbc:mysql://"+ dbHost +":"+ dbPort +"/"+ dbName +"?useSSL=false&serverTimezone=UTC"; 
       
      
      public static void main(String[] args){
          MyClass obj = new MyClass();
          Connection conn = obj.connect();
          try {
                  String sqlString = "SELECT * FROM tutorials_tbl";
                  Statement st = conn.createStatement();
                  ResultSet rs = obj.qurey(st, sqlString);
                          obj.showRet(rs);
                  } catch (SQLException e) {
                          System.out.println("执行失败");
                          e.printStackTrace();
                  }
      }
      
      // 链接
      protected Connection connect () {
          Connection conn = null;
          try{
                Class.forName(MyClass.driverStr);  // 加载驱动
                conn = DriverManager.getConnection(MyClass.connStr,MyClass.dbUserName,MyClass.dbPassword); // 连接
                System.out.println("连接成功");
              }catch(Exception ex){
                System.out.println("连接失败");
                System.out.println(ex.toString());
          }
          
          return conn;
          }
      
      // 查询
      protected ResultSet qurey(Statement stmt,String sql) {
          ResultSet rs = null;
          try {
                rs = stmt.executeQuery(sql);
                System.out.println("查询成功");
              } catch (SQLException e) {
                // TODO Auto-generated catch block
                System.out.println("查询失败");
                e.printStackTrace();
              }
          
          return rs;
      }
      
      // 遍历结果
      
      protected void showRet(ResultSet rs) {
          try {
                while(rs.next()){
                  System.out.println(rs.getInt("tutorial_id")+"\t\t"+rs.getString("tutorial_title")+ "\t\t"+ rs.getString("tutorial_author") +"\t\t"+ rs.getString("submission_date"));
                }
              } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
              }
  
          }
  }

  尝试一下

  提示：不懂编译的同学查看：数据库连接一章