Java之jdbc_採用Statement查詢所有數據

動力節點筆記

 

import java.sql.*;
//採用Statement查詢所有數據
public class QueryTest03 {
    public static void main(String[] args) {
        Connection conn = null;
        Statement stmt = null;
        ResultSet rs = null;
        try {
            //第一步，加載數據庫驅動，不一樣的數據庫驅動程序不同
            Class.forName("oracle.jdbc.driver.OracleDriver");
            //第二部，獲得數據庫鏈接
            String dburl = "jdbc:oracle:thin:@localhost:1521:orcl";
            //String dburl = "jdbc:oracle:thin:@192.168.21.1:1521:orcl";
            //String dburl = "jdbc:oracle:thin:@127.0.0.1:1521:orcl";
            String userName = "system";
            String password = "wanwan";
            conn = DriverManager.getConnection(dburl, userName, password);
            //System.out.println(conn);

            //第三步，建立Statement，執行SQL語句
            stmt = conn.createStatement();
            //第四部，取得結果集
            rs = stmt.executeQuery("select * from tb_student");
            while (rs.next()) {
                int id = rs.getInt("id");
                String name = rs.getString("name");
                System.out.println(id + " , " + name);
            }

            System.out.println("============================");
            //能夠採用索引號取得字段的值，索引從1開始，
            //儘可能不要使用索引號的方式，由於不明確
            rs = stmt.executeQuery("select * from tb_student");
            while (rs.next()) {
                int id = rs.getInt(1);
                String name = rs.getString(2);
                System.out.println(id + "," + name);
            }

        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            //注意關閉原則：從裏到外


            try {
                if (rs != null) {
                rs.close();
                }
                if (stmt != null) {
                    stmt.close();
                }
                    if (conn != null) {
                    conn.close();
                    }
            } catch(SQLException e) {

            }

        }
    }
}