Net上机考试

No.53取出表A中第31到第40

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data;
using System.Data.SqlClient;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        { 
           
            InitializeComponent();  
           
        }
          
        private void button1_Click(object sender, EventArgs e)
        {
            string str ="Data Source=rj1-13;Initial Catalog=UserSelect;Integrated Security=True";
            SqlConnection conn = new SqlConnection(str);
            conn.Open();
            string Sqlstr = "select top 10 * from A where id not in (select top 30 id from A)";
            SqlCommand comm = new SqlCommand(Sqlstr, conn);
            SqlDataReader reader = comm.ExecuteReader();
            while (reader.Read())
            {
                //int id = int.Parse(reader["ID"].ToString());
                string id = reader["ID"].ToString();
                string name = reader["Usename"].ToString();
                string Age = reader["UserAge"].ToString();
                string sex = reader["useSex"].ToString();
                ListViewItem lvi = new ListViewItem(id);
                lvi.SubItems.Add(name);
                lvi.SubItems.Add(Age);
                lvi.SubItems.Add(sex);
                listView1.Items.Add(lvi);
               
            }
            comm.Clone();

        }
    }
}





//SqlDataAdapter da = new SqlDataAdapter(Sqlstr, str);
// DataSet ds = new System.Data.DataSet();
// da.Fill(ds);
// this.dataGridView1.DataSource = ds.Tables[0];

sql语句

create database UserSelect

use UserSelect
go

create table A
(
    ID int identity(1,1),
    Usename varchar (20),
    useSex varchar(20),
    UserAge varchar(4)
)


insert into A values('张三1','男','20')

insert into A values('张三2','男','20')

insert into A values('张三3','男','20')

insert into A values('张三4','男','20')

insert into A values('张三5','男','20')

insert into A values('张三6','男','20')

insert into A values('张三7','男','20')

insert into A values('张三8','男','20')

insert into A values('张三9','男','20')

insert into A values('张三10','男','20')

insert into A values('张三11','男','20')

insert into A values('张三12','男','20')

insert into A values('张三13','男','20')

insert into A values('张三14','男','20')

insert into A values('张三15','男','20')

insert into A values('张三16','男','20')

insert into A values('张三17','男','20')

insert into A values('张三18','男','20')

insert into A values('张三19','男','20')

insert into A values('张三20','男','20')

insert into A values('张三21','男','20')

insert into A values('张三22','男','20')

insert into A values('张三23','男','20')

insert into A values('张三24','男','20')

insert into A values('张三25','男','20')

insert into A values('张三26','男','20')

insert into A values('张三27','男','20')

insert into A values('张三28','男','20')

insert into A values('张三29','男','20')

insert into A values('张三30','男','20')

insert into A values('张三31','男','20')

insert into A values('张三32','男','20')

insert into A values('张三33','男','20')

insert into A values('张三34','男','20')

insert into A values('张三35','男','20')

insert into A values('张三36','男','20')

insert into A values('张三37','男','20')

insert into A values('张三38','男','20')

insert into A values('张三39','男','20')

insert into A values('张三40','男','20')

insert into A values('张三41','男','20')

insert into A values('张三42','男','20')

insert into A values('张三43','男','20')

insert into A values('张三44','男','20')

insert into A values('张三45','男','20')
select * from A


--select top 2 * from A where ID > (select max(ID) from (select top 7 ID from A)

select top 10 * from A where id not in (select top 30 id from A)

No.56 override与重载的区别

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace Example07
{
    class Program
    {
        class BaseClass
        {
            public virtual void F()
            {
                Console.WriteLine("BaseClass.F");
            }
        }
        class DeriveClass : BaseClass
        {
            public override void F()
            {
                base.F();
                Console.WriteLine("DeriveClass.F");
            }
            public void Add(int Left, int Right)
            {
                Console.WriteLine("Add for Int: {0}", Left + Right);
            }
            public void Add(double Left, double Right)
            {
                Console.WriteLine("Add for int: {0}", Left + Right);
            }
        }
        static void Main(string[] args)
        {
            DeriveClass tmpObj = new DeriveClass();
            tmpObj.F();
            tmpObj.Add(1, 2);
            tmpObj.Add(1.1, 2.2);

            Console.ReadLine();
        }
    }
}

No.57net 的错误处理机制

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            string str = "Data Source=rj1-13;Initial Catalog=Aelect;Integrated Security=True";
            SqlConnection conn = new SqlConnection(str);
            string sql = string.Format("select * from Users");
            try
            {
                SqlCommand cmd = new SqlCommand(sql,conn);
                conn.Open();
                SqlDataReader dr = cmd.ExecuteReader();
                while (dr.Read())
                {
                    string id = dr["ID"].ToString();
                    string Name = dr["Usename"].ToString();
                    string age = dr["UserAge"].ToString();
                    string  sex= dr["useSex"].ToString();

                    ListViewItem lvi = new ListViewItem(id);
                    lvi.SubItems.Add(Name);
                    lvi.SubItems.Add(age);
                    lvi.SubItems.Add(sex);
                    listView1.Items.Add(lvi);
     
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
                throw;
            }
            finally
            {
                conn.Close();
            }
          
        }
        
    }
}

create database Aelect

use Aelect
go

create table Users
(
    ID int identity(1,1),
    Usename varchar (20),
    useSex varchar(20),
    UserAge varchar(4)
)


insert into Users values('张三1','男','20')

insert into Users values('张三2','男','20')

insert into Users values('张三3','男','20')

insert into Users values('张三4','男','20')

insert into Users values('张三5','男','20')

insert into Users values('张三6','男','20')

insert into Users values('张三7','男','20')

insert into Users values('张三8','男','20')

insert into Users values('张三9','男','20')

insert into Users values('张三10','男','20')

insert into Users values('张三11','男','20')

insert into Users values('张三12','男','20')

insert into Users values('张三13','男','20')

insert into Users values('张三14','男','20')

insert into Users values('张三15','男','20')

insert into Users values('张三16','男','20')

insert into Users values('张三17','男','20')

insert into Users values('张三18','男','20')

insert into Users values('张三19','男','20')

insert into Users values('张三20','男','20')

insert into Users values('张三21','男','20')



select * from Users


--select top 2 * from Users where ID > (select max(ID) from (select top 7 ID from Users)

select top 10 * from Users where ID not in (select top 5 ID from Users)

No.60Calss和strut结构体区别

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    namespace 类对象
    {

        //枚举  
        public enum Gender
        {
            男,
            女
        }
        //结构体
        public struct stuPerson
        {
            public string stuName;
            public int stuAge;
            public Gender stuSex;
            public void stuSayHello()
            {
                Console.WriteLine("我是{0},年龄{1},性别{2}", stuName, stuAge, stuSex);
            }

            //必须定义有参数的构造函数
            public stuPerson(string name, int age, Gender sex)
            {
                this.stuName = name;
                this.stuAge = age;
                this.stuSex = sex;
            }

        }
        class Program
        {
            static void Main(string[] args)
            {
                //实例化类
                Person Liuxiang = new Person();  //无参数的构造函数实例化的对象
                Liuxiang.Name = "刘翔";
                Liuxiang.Age = 30;
                Liuxiang.Sex = Gender.男;
                Liuxiang.SayHello();
                //声明另一个实例
                Person LXSon = Liuxiang;
                LXSon.Age = 10;
                //查看类 LiuXiang 和 LXSon中字段的值
                Console.WriteLine("LiuXiang 年龄{0}", Liuxiang.Age.ToString());  //10
                Console.WriteLine("LXSon 年龄{0}", LXSon.Age.ToString());    //10

                Console.WriteLine();
                //结构体
                stuPerson YaoMing = new stuPerson("姚明", 33, Gender.男);
                YaoMing.stuSayHello();
                stuPerson YMSon = YaoMing;
                YMSon.stuAge = 13;
                //查看结构体中 YaoMing 和 YMSon中字段的值
                Console.WriteLine("YaoMing 年龄{0}", YaoMing.stuAge.ToString());  //10
                Console.WriteLine("YMSon 年龄{0}", YMSon.stuAge.ToString());    //10

                Console.ReadLine();



            }

        }

        class Person
        {

            //定义字段
            public string Name;
            public int Age;
            public Gender Sex;

            //定义方法
            public void SayHello()
            {
                Console.WriteLine("我是{0},年龄{1},性别{2}", this.Name, this.Age, this.Sex);
            }
            //无参数的构造函数
            public Person()
            {

            }
            //有参数的构造函数
            public Person(string name, int age, Gender sex)
            {
                this.Name = name;
                this.Age = age;
                this.Sex = sex;
            }


        }
    }
}