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','admin@bdqn.cn',0);
INSERT INTO NEWS_USER VALUES(2,'user','user','user@bdqn.cn',1);
INSERT INTO NEWS_USER VALUES(3,'test','test','test@bdqn.cn',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();

    }

}