如何在JDBC中对表的内容进行排序？

对表的内容进行排序意味着以有组织的方式重新排列记录以使数据更有用。您可以通过选择表中的列来对表的所有记录进行排序，以根据必须对哪些数据进行排序。简而言之，当您对数据进行排序时，就是按照逻辑顺序排列数据。

• 文本和数字都可以按任何顺序排序，即升序或降序。
• 可以同时对一列或多列进行排序。
• 在 SQL 中，ORDER BY 子句用于对 JDBC 中的表的内容进行排序。
• 默认情况下，某些数据库按升序对查询进行排序。但是我们也可以按降序排序。
• 我们可以同时对一列或多列使用 ORDER BY 子句。

要遵循的步骤：

1. 导入必要的库
2. 注册驱动程序类
3. 通过提供地址、用户名和密码连接到您的数据库
4. 创建您的声明
5. 写下您的查询
6. 执行查询并将结果存储在结果集中
7. 显示结果

How ORDER BY works:
       
   query ----->       select * from Table_Name ORDER BY Column1,Column 2; 
   
   user table ----->  --------------------------------------------------
                 ||     id      ||      Name     ||     Age      ||
                 ||      1      ||      Prateek  ||     20       ||
                 ||      4      ||      Chhavi   ||     21       ||
                 ||      3      ||      Aman     ||     22       ||
                 ||      2      ||      Kartikay ||     22       ||
                 ||      5      ||      Prakhar  ||    20        ||
                 --------------------------------------------------
   
   Example 1:         select * from user ORDER BY id;
  
   Output:           --------------------------------------------------
                 ||     id      ||      Name     ||     Age      ||
                 ||      1      ||      Prateek  ||     20       ||
                 ||      2      ||      Kartikay ||     22       ||
                 ||      3      ||      Aman     ||     22       ||
                 ||      4      ||      Chhavi   ||     21       ||
                 ||      5      ||      Prakhar  ||     20       ||
                 --------------------------------------------------

   Example 2:         select * from user ORDER BY name,age;
  
   Output:           --------------------------------------------------
                 ||     id      ||      Name     ||     Age      ||
                 ||      3      ||      Aman     ||     22       ||
                 ||      4      ||      Chhavi   ||     21       ||
                 ||      2      ||      Kartikay ||     22       ||     
                 ||      5      ||      Prakhar  ||     20       ||
                 ||      1      ||      Prateek  ||     20       ||
                 --------------------------------------------------

示例 1：

Java

// Java program to sort contents of a table 
  
import java.sql.*;
  
public class GFG {
  
    // driver code
    public static void main(String[] args) throws Exception
    {
  
        // Register Driver Class
        Class.forName("org.apache.derby.jdbc.ClientDriver");
  
        // Connection to your database, pass all the
        // necessary parameters such as address , username &
        // password
        Connection con = DriverManager.getConnection();
  
        // Create Statement
        Statement stmt = con.createStatement();
  
        // Query to be executed
        String query = "Select * from users ORDER by id";
  
        // Execute SQL query and store the result in any
        // variable
        ResultSet rs = stmt.executeQuery(query);
  
        System.out.println("Id    Name    Age");
        while (rs.next()) {
            int id = rs.getInt("id");
            String name = rs.getString("name");
            int age = rs.getInt("age");
            System.out.println(id + "  " + name + "   "
                               + age);
        }
  
        // close the connection
        con.close();
    }
}

输出

示例 2：

Java

// Java program to sort contents of a table 
  
import java.sql.*;
  
public class GFG {
  
    // driver code
    public static void main(String[] args) throws Exception
    {
  
        // Register Driver Class
        Class.forName("org.apache.derby.jdbc.ClientDriver");
  
        // Connection to your database, pass all the
        // necessary parameters such as address , username &
        // password
        Connection con = DriverManager.getConnection();
  
        // Create Statement
        Statement stmt = con.createStatement();
  
        // Query to be executed
        String query
            = "Select * from users ORDER by name,age";
  
        // Execute SQL query and store the result in any
        // variable
        ResultSet rs = stmt.executeQuery(query);
  
        System.out.println("Id    Name    Age");
        while (rs.next()) {
            int id = rs.getInt("id");
            String name = rs.getString("name");
            int age = rs.getInt("age");
            System.out.println(id + "  " + name + "   "
                               + age);
        }
  
        // close the connection
        con.close
    }
}

输出

注意：我们不能使用 Prepared Statement 对表的内容进行排序。准备好的语句与绑定变量一起发出 SQL 语句，因此它不能用于列名或表名。