package jdbc;

 import java.sql.Connection;

 import java.sql.Driver;

 import java.sql.DriverManager;

 import java.sql.ResultSetMetaData;

 /**

  * @author liuwenlong

  * @create 2020-08-11 14:36:20

  */

 @SuppressWarnings("all")

 public class LwlSql {

     public static void main(String[] args) {

         Connection conn = null;

         try {

             //第一步，测试是否已经添加了操作oracle的jar包

             Class.forName("oracle.jdbc.driver.OracleDriver");

             //第二步：和数据库连接

             conn = DriverManager.getConnection("jdbc:oracle:thin:@192.168.1.3:1521:xe", "lwl", "123456");

             //第三步，创建执行sql语句的对象

             java.sql.Statement st = conn.createStatement();

             java.sql.ResultSet rs = null;

             byte[] b = new byte[300];

             String sql = null;

             while (true) {

                 try {

                     System.out.println("jwlSql>");

                     int len = System.in.read(b);

                     if (len < 5) {

                         System.err.println("invalid sql");

                         continue;

                     }

                     if (b[len - 2] == 13 && b[len - 1] == 10) {

                         len = len - 2;

                     } else {

                         len = len - 1;

                     }

                     sql = new String(b, 0, len);

                     if (sql.equals("exit") || sql.equals("quit")) {

                         System.out.println("welcome again!!");

                         return;

                     }

                     //查询

                     if (sql.startsWith("select")) {

                         rs = st.executeQuery(sql);

                         ResultSetMetaData md = rs.getMetaData();

                         int fld = md.getColumnCount();

                         for (int i = 1; i <= fld; i++) {

                             System.out.print(md.getColumnName(i) + "\t");//显示列名字

                         }

                         System.out.println();

                         while (rs.next()) {//显示数据

                             for (int i = 1; i <= fld; i++) {

                                 System.out.print(rs.getString(i) + "\t\t");

                             }

                             System.out.println();

                         }

                     } else {

                         st.executeUpdate(sql);

                     }

                 } catch (Exception e) {

                     System.err.println(e.getMessage());

                 }

             }

         } catch (Exception e) {

             System.err.println(e.getMessage());

         }

     }

 }