Java的基础知识
1.用java做一个两个数相加求和的程序(命令行的即可)
import java.util.Scanner; //方法一 public class Demo2 { public static void main(String[] args) { Scanner sc =new Scanner(System.in); System.out.println("请输入第一个整数:"); int a=sc.nextInt(); System.out.println("请输入第二个整数:"); int b =sc.nextInt(); int sum =a+b; System.out.println("它们的和为:"+sum); } }
import java.util.Scanner; //方法二 public class Demo1 { public static void main(String[] args) { // TODO Auto-generated method stub Scanner sc =new Scanner(System.in); System.out.println("请输入第一个数"); int m =sc.nextInt(); System.out.println("请输入第二个数"); int n=sc.nextInt(); System.out.println("两个数的和是"+ (m+n)); } }
2.然后写SQL语句新建一个表,插入一笔数据,修改一笔数据,删除一笔数据
CREATE DATABASE db0504; USE db0504; CREATE TABLE student ( sno VARCHAR (10) NOT NULL UNIQUE PRIMARY KEY, sname VARCHAR (20) NOT NULL, ssex enum ('男', '女') NOT NULL DEFAULT '男', sbirth date, sclass VARCHAR (10), zno CHAR (4) ) DEFAULT charset = gb2312; #添加操作 INSERT INTO student VALUES('2012010713','丁暖','女','1993-9-9','物联网12-1','z002'); INSERT INTO student (sno,sname,ssex,sbirth,sclass,zno) VALUES('2011010503','孔超','男','1993-9-19','自动化11-1','z006'); INSERT INTO student (sno, sname, ssex, zno) VALUES('2011010521','韩梅','女','z006'); INSERT INTO student (sname, zno, sno) VALUES('韩梅2','z006','2011010522'); INSERT INTO student VALUES ('2011010501','孔超1','男','1993-9-19','自动化11-1','z006'); ('2011010505','孔超2','男','1993-9-19','自动化11-1','z006'); ('2011010504','孔超3','男','1993-9-19','自动化11-1','z006'); ('2011010505','孔超4','男','1993-9-19','自动化11-1','z006'); #修改操作 UPDATE student SET sname = '张三',sbirth = '1993-6-19' WHERE sname = '丁暖'; UPDATE student SET zno = LEFT (zno, 3); #删除操作 delete from student where sname='张三'; #查询操作 SELECT * FROM student;#查询student表的所有记录 SELECT sno,sname,ssex,sbirth FROM student;#查询部分字段信息 SELECT * FROM student WHERE age BETWEEN 25 AND 30; #清空表操作 truncate student;#高效 delete from student;
3.用java做一个查询数据库的程序(命令行的即可,数据库随便一种都可以)
class SqlConnectionUtil { public static void main(String[] args) { Connection conn = null; Statement stmt = null; ResultSet rs = null; String sql; String url = "jdbc:MySQL://localhost:3306/test?user=root&password=root&useUnicode=true&characterEncoding=UTF8"; try { Class.forName("com.MySQL.jdbc.Driver"); conn = DriverManager.getConnection(url); stmt = conn.createStatement(); sql = "select * from user"; rs = stmt.executeQuery(sql); while (rs.next()) { String name = rs.getString("name"); System.out.println("姓名是:" + name); } } catch (Exception e) { e.printStackTrace(); } finally { if (rs != null) { try { rs.close(); } catch (SQLException e) { e.printStackTrace(); } } if (stmt != null) { try { stmt.close(); } catch (SQLException e) { e.printStackTrace(); } } if (conn != null) { try { conn.close(); } catch (SQLException e) { e.printStackTrace(); } } } } }