JDBC

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本文提供了一个使用 Java JDBC 连接 MySQL 数据库并查询 tb_user 表的示例代码。该示例展示了如何加载 JDBC 驱动、建立连接、执行 SQL 查询及处理结果集。

package test;

import java.sql.*;

public class JDBC {
   // JDBC driver name and database URL
   static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";  
   static final String DB_URL = "jdbc:mysql://localhost/bj?useUnicode=true&characterEncoding=UTF-8";

   //  Database credentials -- 数据库名和密码
   static final String USER = "***";
   static final String PASS = "***";

   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,username,password from tb_user";//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");
         String username = rs.getString("username");
         String password =rs.getString("password");
         //Display values
         System.out.print("\nID: " + id+"  ");
         System.out.println("\nUSENAME: " + username);
         System.out.print("PASSWORD: " + password+"\n");


      }
      //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