SQLite3创建和简单使用说明

package sqlite;

import java.sql.Statement;

import java.util.Scanner;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.SQLException;

/**

 * 使用sqlit3

 * 如果想使用sqlite3这个android自带的数据库
首先需要将在硬盘里面创建一个db文件夹，然后通过cmd命令提示符

SQLite
D:/android/db/

或者

D:

cd android/db

sqlite3 student.db

.database

以分号;结束

以点.开头的都是命令

建立一个小型数据库，然后再创建一个表

--创建表student

CREATE TABLE student(
id integer,
name text,
age,integer

);

然后就可以使用程序对这个数据库进行操作了

 *增删改查相关的语句

 *

 --向student表中添加一列性别gender

ALTER TABLE student ADD COLUMN gender text;

--插入一条数据--

INSERT INTO 表名（列1，列2，列3）BALUES(值1，值2，值3）;

--修改数据----------------------------

update man set gender='男'where name='梅鑫';

-------------删除数据--------------

delete from man where id=10000;

------------查询-----------------

select * from man;

--select 列名   from 表名 where 条件

select * from man where age>=25;

select * from man where age>=25 and age<=35;

select * from man between 23 and 35;

select * from man where age!=35;

select * from man where age<>25;

--查询所有姓张的学生----模糊查询like

select * from man where name like '%张%';

----------查询前3条数据-----------------

select * from man limit 3;

select * from man limit 3,3; ---从第4条开始然后数3条

-----------------------------------------------------

-----查询所有英雄，按照年龄升序(降序desc)排序-------------

select * from man order by age asc;

--------按照年龄降序，年龄相同，则按照id升序排序-----------

select * from man order by age dest,id asc;

------------查询年龄最大的英雄姓名-----------------

select name from man order by age desc limit 1;

---聚合函数   sum() avg() max() min() count()

---求所有的英雄人数

select count(id)"英雄人数" from man;

select count(id) as "英雄人数" from man;

---求所有英雄年龄总和

select sum(age) from man;

select name,min(age) from man;

-----------------------------------------------------------

--------查询男生和女生个数

select gender,count(gender)from student group by gender;

select * from man group by gender;

---查询年龄大于平均年龄的英雄信息   子查询

select * from man where age>(select avg(age) from man);

select avg(age) from man;

--查询英雄姓名和所在国家名称

select man.name 英雄姓名,contry.name 国家姓名 form man,contry where man.cid=contry.cid;

--删除重复数据，只保留一个数据

delete from man where rowid not in(select max(rowid) rowid from man group by id);

 */

public class Login {

public static void main(String[] args) {
// TODO Auto-generated method stub
//add();
login();
}
public static void login(){
Scanner in=new Scanner(System.in);
System.out.println("请输入用户名：");
String name=in.nextLine();
System.out.println("请输入密码");
String pwd=in.nextLine();

String sql="select * from word where name='"+name+"'and password='"+pwd+"'";
try {
Class.forName("org.sqlite.JDBC");
Connection conn=DriverManager.getConnection("jdbc:sqlite:D:\\android\\db\\jin.db");
Statement stmt=conn.createStatement();
ResultSet rs=stmt.executeQuery(sql);
if(rs.next()){
System.out.println("登录成功");
}else{
System.out.println("登录失败");
}
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

}
public static  void add(){
try {
Class.forName("org.sqlite.JDBC");
Connection conn=DriverManager.getConnection("jdbc:sqlite:D:\\android\\db\\jin.db");
String sql="insert into word values('ashen','ashen')";
//String sql="delete from word where rowid not in(select max(rowid) rowid from word group by name)";
Statement stmt=conn.createStatement();
int result=stmt.executeUpdate(sql);
if(result>0){
System.out.println("已经成功加进来");
}else{
System.out.println("失败了");
}
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

}

}