JDBC 选择记录

JDBC教程 - JDBC选择记录

以下代码显示如何从数据库表中检索数据。

它发出一个select命令，并通过读取 ResultSet 获取结果接口。

例子

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

public class Main {
  static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";
  static final String DB_URL = "jdbc:mysql://localhost/STUDENTS";

  static final String USER = "username";
  static final String PASS = "password";

  public static void main(String[] args) throws Exception {
    Connection conn = null;
    Statement stmt = null;

    Class.forName(JDBC_DRIVER);
    conn = DriverManager.getConnection(DB_URL, USER, PASS);
    System.out.println("Deleting database...");
    stmt = conn.createStatement();

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

    stmt = conn.createStatement();
    String sql = "SELECT id, first, last, age FROM Person";
    ResultSet rs = stmt.executeQuery(sql);
    while (rs.next()) {
      // Retrieve by column name
      int id = rs.getInt("id");
      int age = rs.getInt("age");
      String first = rs.getString("firstName");
      String last = rs.getString("lastName");

      // Display values
      System.out.print("ID: " + id);
      System.out.print(", Age: " + age);
      System.out.print(", First: " + first);
      System.out.println(", Last: " + last);
    }
    rs.close();
    stmt.close();
    conn.close();
  }
}

示例PreparedStatement

以下代码显示了如何使用Oracle JDBC驱动程序通过PreparedStatement执行select语句。

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

public class Main {
  private static final String DB_DRIVER = "oracle.jdbc.driver.OracleDriver";
  private static final String DB_CONNECTION = "jdbc:oracle:thin:@localhost:1521:YourDatabase";
  private static final String DB_USER = "user";
  private static final String DB_PASSWORD = "password";

  public static void main(String[] argv) throws Exception {
    Connection dbConnection = null;
    PreparedStatement preparedStatement = null;
    Class.forName(DB_DRIVER);
    dbConnection = DriverManager.getConnection(DB_CONNECTION, DB_USER,
        DB_PASSWORD);

    String selectSQL = "SELECT USER_ID, USERNAME FROM Person WHERE USER_ID = ?";
    preparedStatement = dbConnection.prepareStatement(selectSQL);
    preparedStatement.setInt(1, 1001);

    ResultSet rs = preparedStatement.executeQuery();

    while (rs.next()) {

      String userid = rs.getString("USER_ID");
      String username = rs.getString("USERNAME");

      System.out.println("userid : " + userid);
      System.out.println("username : " + username);

    }

    preparedStatement.close();
    dbConnection.close();

  }
}