NewLibrary/Book_manger/Sql/Form3.cs

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

namespace Sql
{
    public partial class Form3 : Form
    {
        string SID;
        public Form3(string sID)
        {
            SID = sID;
            InitializeComponent();
            toolStripStatusLabel2.Text = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss");
            toolStripStatusLabel1.Text = "欢迎学号为" + SID + "的同学登录图书借阅系统";
            timer1.Start();
            Table();
        }
        public void Table()                   //此私有类是将数据加载到窗体中
        {
            dataGridView1.Rows.Clear();           //清除前面的数据，方便后面重新刷新数据
            string sql = "select * from Book";
            Dao dao = new Dao();
            IDataReader dr = dao.read(sql);
            while (dr.Read())
            {
                string a, b, c, d, e,f,g,h;
                a = dr["Id"].ToString();           //这例可以自己修改
                b = dr["Name"].ToString();
                c = dr["Author"].ToString();
                d = dr["DOP"].ToString();
                e = dr["Count"].ToString();
                f = dr["Publisher"].ToString();
                g = dr["Category"].ToString();
                h = dr["State"].ToString();
                string[] str = { a, b, c, d, e,f,g,h};
                dataGridView1.Rows.Add(str);       //添加数据               
            }
            dr.Close();//关闭连接
        }

        private void timer1_Tick(object sender, EventArgs e)
        {
            toolStripStatusLabel2.Text = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss");
        }

        private void Form3_FormClosed(object sender, FormClosedEventArgs e)      
        {
            Application.Exit();      //***非常重要：上面的Form3_FormClosed就是Form3右上方的那个叉叉，单击后整个程序及所有窗口都会关闭
        }

        private void 借阅ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            string BookId = dataGridView1.SelectedCells[0].Value.ToString();//获取选中的图书号
            string sql1 = "select * from BookRecord where sID='" + SID + "'and BookId='" + BookId + "'";//查询是否已经借阅了这本书
            Dao dao = new Dao();
            IDataReader dc = dao.read(sql1);      //IDataReader是什么意思?是可以进行数据库操作的对象的意思
            DialogResult r = MessageBox.Show("是否确认借阅", "提示", MessageBoxButtons.OKCancel);

            if (!dc.Read() && r == DialogResult.OK)
            {
                string sql5 = "select Count from BookRecord where sID='" + SID + "'";//查询该同学借阅了多少书籍
                Dao dao5 = new Dao();
                IDataReader dc5 = dao.read(sql5);
                dc5.Read();
                string bcount = dc5["Count"].ToString();//bcount借过的图书数量
                string s2 = "5";

                if (s2.CompareTo(bcount) == 1)//5和借阅数量比较，首先5大，然后成立，bcount+1，一直加假如5=5，那么不给再继续借了
                {


                    //这里要加一个查询book表的代码
                    string BId = dataGridView1.SelectedCells[0].Value.ToString();
                    string Author = dataGridView1.SelectedCells[1].Value.ToString();
                    string Count = dataGridView1.SelectedCells[4].Value.ToString();
                    string jytime = DateTime.Now.ToString("yyyy - MM - dd HH: mm:ss");
                    string ghtime = DateTime.Now.AddMonths(3).ToString("yyyy - MM - dd HH: mm:ss");
                    string sql2 = "update Book set Count = '" + Count + "' - 1 WHERE  Id = '" + BId + "' ";
                    int i2 = dao.Execute(sql2);

                    if (i2 > 0)//图书数量大于的话就执行下面的
                    {
                        string sql = "insert into BookRecord(BookId,BookName,jytime,ghtime ,SID ) values('" + BId + "','" + Author + "','" + jytime + "','" + ghtime + "','" + SID + "')";
                        int i = dao.Execute(sql);
                        string sql3 = "UPDATE BookRecord SET Count = Count+1 WHERE SID = " + SID + " ";
                        int i3 = dao.Execute(sql3);//更新图书记录表，给相应用户的图书数量+1
                        MessageBox.Show("借阅成功");
                    }
                    else
                    {
                        MessageBox.Show("图书库存不足！");
                    }
                }
                else
                {
                    MessageBox.Show("借阅数量已达五本，请先还书再借阅！");
                }
            }
            else if (!dc.Read() && r == DialogResult.Cancel)
            {
                //无需任何操作
            }
          /*  else if(i2 < 0)//这个就是i2没有执行成功后来到这里
            {
                MessageBox.Show("图书库存不足");
            }*/
            else
            {
                MessageBox.Show("你已经借阅了该图书！");
            }
        }

        private void Form3_Load(object sender, EventArgs e)
        {

        }

        private void 我的借阅ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            Form31 f = new Form31(SID);
            f.Show();      //打开form31窗口
        }

        private void 搜索图书ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            string B = textBox1.Text;
            string C = comboBox1.Text;//图书类型
            Form32 f = new Form32(SID, B, C);
            f.Show();      //打开form32窗口
        }
        private void 退出当前账号ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            DialogResult hh = MessageBox.Show("                  是否确定退出当前账号", "提示", MessageBoxButtons.OKCancel);
            if(hh == DialogResult.OK)
            {
                Form1 form1 = new Form1();
                form1.Show();
                this.Hide();
            }
            else
            {
                //无需任何操作
            }
        }
    }
}