如何编辑（添加或更新）表中的列，以及如何删除 Java 中的表

问题说明

如何编辑（添加或更新）表中的列，以及如何删除表？

解决方案

以下示例使用 create、alter 和 drop SQL 命令来创建、编辑或删除表。

import java.sql.*;

public class jdbcConn {
   public static void main(String[] args) throws Exception { 
      Class.forName("org.apache.derby.jdbc.ClientDriver");
      Connection con = DriverManager.getConnection(
         "jdbc:derby://127.0.0.1:1527/testDb","username", "password");
      
      Statement stmt = con.createStatement();
      String query ="CREATE TABLE employees(id INTEGER PRIMARY KEY, first_name CHAR(50), last_name CHAR(75))";
      
      stmt.execute(query);
      System.out.println("Employee table created");
      String query1 = "aLTER TABLE employees ADD address CHAR(100) ";
      String query2 = "ALTER TABLE employees DROP COLUMN last_name";
      
      stmt.execute(query1);
      stmt.execute(query2);
      System.out.println("Address column added to the table & last_name column removed from the table");
      
      String query3 = "drop table employees";
      stmt.execute(query3);
      System.out.println("Employees table removed");
   }	
}

结果

上面代码示例将产生以下结果。结果可能有所不同。

Employee table created
Address column added to the table & last_name 
column removed from the table
Employees table removed from the database