package api8;import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;public class UpdateSelect {public static void main(String[] args) {// jdbc 连接 OracleselectAll();}// 增删改public static int alter(String sql) {Connection conn = null;Statement st = null;try {// 导入连接Oracle jar包 加载驱动Class.forName("oracle.jdbc.OracleDriver");// jdbc 主协议 oracle 子协议 thin模式 @127.0.0.1 本机地址 1521 oracle这个软件的端口号 orcl本地数据库String url = "jdbc:oracle:thin:@127.0.0.1:1521:orcl";// 创建连接  scott 分别是 登录orcl数据库 的账号密码conn = DriverManager.getConnection(url, "scott", "scott");// 创建命令对象st = conn.createStatement();// 命令对象执行sql语句int i = st.executeUpdate(sql);// 返回sql语句增删改受影响行数。return i;} catch (ClassNotFoundException e) {System.out.println(e);} catch (SQLException e) {System.out.println(e);} finally {try {if (st != null) st.close();if (conn != null) conn.close();} catch (SQLException e) {System.out.println(e);}}return -1;	}// 逐行查询	public static void selectAll() {Connection conn = null;Statement st = null;ResultSet rs = null;try {Class.forName("oracle.jdbc.OracleDriver");String url = "jdbc:oracle:thin:@127.0.0.1:1521:orcl";conn = DriverManager.getConnection(url, "scott", "scott");st = conn.createStatement();String sql = "select * from Users";// 命令对象执行sql查询语句, 返回结果集。rs = st.executeQuery(sql);// 一行一行的读取while (rs.next()) {System.out.println("id:" + rs.getInt("U_ID") + "\t Name:" + rs.getString("U_NAME"));}} catch (ClassNotFoundException e) {System.out.println(e);} catch (SQLException e) {System.out.println(e);} finally {try {if (rs != null)rs.close();if (st != null) st.close();if (conn != null) conn.close();} catch (SQLException e) {System.out.println(e);}// 我把这个方法写死了, 只能对user表查, 对别的表, 可能结构不一样。// 如果我返回结果集 resultSet 别人用时可能忘记关结果集。}}}