JDBC二查询(web基础学习笔记八)

一、建立数据库

--创建news表空间

CREATE TABLESPACE tbs_news

DATAFILE 'F:\ORACLE\news.dbf'

SIZE 10M

AUTOEXTEND ON;

--创建news用户

CREATE USER news IDENTIFIED BY news

DEFAULT TABLESPACE tbs_news;

--授权

GRANT RESOURCE,CONNECT TO news;



--创建表

SELECT * FROM tab;

-----新闻发布系统

-----用户表

drop table NEWS_USER;

create table NEWS_USER(

  id                NUMBER(10, 0)    PRIMARY KEY NOT NULL,  ---用户编号

  username          varchar2(20)     NOT NULL,              ---用户名

  password          varchar2(20)    NOT NULL,              ---密码

  email             varchar2(100)   NULL,

  usertype          number(5,0)     NOT NULL               ----用户类型  0：管理员 1：普通用户

);

INSERT INTO NEWS_USER VALUES(1,'admin','admin','[email protected]',0);

INSERT INTO NEWS_USER VALUES(2,'user','user','[email protected]',1);

INSERT INTO NEWS_USER VALUES(3,'test','test','[email protected]',1);

COMMIT;

SELECT * FROM news_user;



-------新闻分类表， 有外键存在，因此先删除子表

drop table NEWS_COMMENT;

drop table NEWS_DETAIL;

drop table NEWS_CATEGORY;

create table NEWS_CATEGORY(

    id              NUMBER(10,0)     NOT NULL PRIMARY KEY,   --类别ID

    name            varchar2(50)     NOT NULL,                 --类别名称

    createdate      Date             NOT　NULL ---创建时间

);



INSERT INTO NEWS_CATEGORY(id,name,createdate) VALUES(1,'国内',sysdate);

INSERT INTO NEWS_CATEGORY(id,name,createdate) VALUES(2,'国际',sysdate);

INSERT INTO NEWS_CATEGORY(id,name,createdate) VALUES(3,'娱乐',sysdate);

INSERT INTO NEWS_CATEGORY(id,name,createdate) VALUES(4,'军事',sysdate);

INSERT INTO NEWS_CATEGORY(id,name,createdate) VALUES(5,'财经',sysdate); 

INSERT INTO NEWS_CATEGORY(id,name,createdate) VALUES(6,'天气',sysdate); 

COMMIT;



--查询

SELECT * FROM news_category;

-----新闻明细表

create table NEWS_DETAIL(

    id               number(10,0)    NOT NULL  PRIMARY KEY,    --id

    categoryId       number(10,0)    NOT NULL,                 --新闻类别id

    title                  varchar2(100)   NOT NULL,--新闻标题

    summary          varchar2(255)   NULL,                   --新闻摘要

    content          CLOB   NULL,                           --新闻内容

    picpath          varchar2(255)   NULL,                  --新闻图片路径

    author                  varchar2(50)    NULL,--发表者

    createdate       date            NULL,                  --创建时间

    modifydate       date            NULL,                  --修改时间

    Foreign key(categoryId) references NEWS_CATEGORY(id)

);

--插入数据

INSERT INTO NEWS_DETAIL VALUES(1,1,'尼日利亚一架客机坠毁','尼日利亚一架客机坠毁，伤亡惨重','尼日利亚一架客机坠毁，伤亡惨重,10人重伤','','admin',sysdate,sysdate);

SELECT * FROM news_detail;

-----新闻评论表

create table NEWS_COMMENT(

    id               number(10,0)    PRIMARY KEY,            --id

    newsId           number(10,0)    NOT NULL,               --评论新闻id

    content          varchar2(2000),                         --评论内容

    author           varchar2(50),                          --评论者

    ip               varchar2(15),                          --评论ip

    createdate       date,                                  --发表时间

    Foreign key(newsId) references NEWS_DETAIL(id)

);



SELECT * FROM news_detail;

DELETE FROM news_detail WHERE ID=2;

COMMIT;

 二、将oracle的driver导入到web项目中

1. oracle11g为例:D:\app\Administrator\product\11.2.0\dbhome_1\jdbc\lib\ojdbc6.jar
2. 将此ojdbc6.jar复制到项目中新建lib文件夹保存
3. 右击项目选择build path-buil confing--libaries-add jar选择jar包所在路径如news/WebRoot/WEB-INF/lib/ojdbc6.jar点击确定

三、将Driver导入并建立连接

  

    // 建立连接对象

        Connection conn = null;

        // 建立Statement对象

        Statement stmt = null;

        // 建立结果集对象ResultSet

 

使用Class.forName()来导入Driver

//(1)使用Class.forName()加载驱动

Class.forName("jdbc:oracle:thin:@localhos:1521:orcl","news","news")

四、Connection来建立连接

// (2)使用DriverManager.getconnection(url,用户名，密码)建立连接返回类型是Connection类型

            conn = DriverManager.getConnection(

                    "jdbc:oracle:thin:@localhost:1521:orcl", "news", "news");

五、写SQL并执行

// (3)编写查询sql语句

            String sql = "SELECT c.name,d.title,d.summary,d.content,d.author,d.createdate,d.modifydate FROM news_detail d,news_category c WHERE d.categoryid=c.id ";

            // (4)建立Statement对象,将sql语句导入，使用结果集来接收

            stmt = conn.createStatement();

            rs = stmt.executeQuery(sql);

六、遍历结果集输出

// (5)遍历结果集

            // 首先声明变量用来存放结果集中的字段

            System.out.println("===========新闻列表================");

            while(rs.next()){

            String catename = rs.getString("name");

            String title = rs.getString("title");

            String summary = rs.getString("summary");

            String content = rs.getString("content");

            String author = rs.getString("author");

            Date createdate = rs.getDate("createdate");

            Timestamp modifydate = rs.getTimestamp("modifydate");

            

            

            System.out.println(catename + "\t" + title + "\t" + summary + "\t"

                    + content + "\t" + author + "\t" + createdate + "\t"

                    + modifydate);

以上完整代码:

package pb.news;



import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

import java.sql.Timestamp;

import java.util.Date;



public class newstest {



    public void select() {

        // 建立连接对象

        Connection conn = null;

        // 建立Statement对象

        Statement stmt = null;

        // 建立结果集对象ResultSet

        ResultSet rs = null;

        try {

            // （1）使用Class.forName来导入drive

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

            // (2)使用DriverManager.getconnection(url,用户名，密码)建立连接返回类型是Connection类型

            conn = DriverManager.getConnection(

                    "jdbc:oracle:thin:@localhost:1521:orcl", "news", "news");

            // (3)编写查询sql语句

            String sql = "SELECT c.name,d.title,d.summary,d.content,d.author,d.createdate,d.modifydate FROM news_detail d,news_category c WHERE d.categoryid=c.id ";

            // (4)建立Statement对象,将sql语句导入，使用结果集来接收

            stmt = conn.createStatement();

            rs = stmt.executeQuery(sql);

            // (5)遍历结果集

            // 首先声明变量用来存放结果集中的字段

            System.out.println("===========新闻列表================");

            while(rs.next()){

            String catename = rs.getString("name");

            String title = rs.getString("title");

            String summary = rs.getString("summary");

            String content = rs.getString("content");

            String author = rs.getString("author");

            Date createdate = rs.getDate("createdate");

            Timestamp modifydate = rs.getTimestamp("modifydate");

            

            

            System.out.println(catename + "\t" + title + "\t" + summary + "\t"

                    + content + "\t" + author + "\t" + createdate + "\t"

                    + modifydate);

            }

        } catch (ClassNotFoundException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        } catch (SQLException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        } finally {

            try {

                rs.close();

                stmt.close();

                conn.close();

            } catch (SQLException e) {

                // TODO Auto-generated catch block

                e.printStackTrace();

            }

        }



    }



    public static void main(String[] args) {

        newstest nt = new newstest();

        nt.select();



    }



}