FrmStudentList.cs

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

namespace WinStudent
{
    public partial class FrmStudentList : Form
    {
        public FrmStudentList()
        {
            InitializeComponent();
        }
        //内置委托，Action<int> 可以不带参数，带参数最多16个，不带返回值
        //Fund<int> 可以不带参数，带参数最多16个，带一个返回值
        private Action reLoad = null;
        //单例，只有一个实例
        private static FrmStudentList fStudentList = null;
        public static FrmStudentList CreateInstance()
        {
            if (fStudentList == null || fStudentList.IsDisposed)
            {
                fStudentList = new FrmStudentList();
            }
            
            return fStudentList;
        }
        //加载班级列表和学生信息
        private void FrmStudentList_Load(object sender, EventArgs e)
        {
            LoadClass();//加载班级列表
            LoadAllStudentList();//加载所有学生信息
        }
        //加载所有学生信息
        private void LoadAllStudentList()
        {
            string sql = "select StuId,StuName,c.ClassName,GradeName,Sex,Phone " +
                "from StudentInfo s inner join ClassInfo c on s.ClassId=c.ClassId " +
                "inner join GradeInfo g on g.GradeId=c.GradeId";
            //sql += " where s.IsDelete=0";//假删除
            //加载数据
            DataTable dtStudentList=SqlHelper.GetDataTable(sql);
            ////组合班级列表显示项的过程
            if (dtStudentList.Rows.Count > 0)
            {
                foreach (DataRow dr in dtStudentList.Rows)
                {
                    string className = dr["ClassName"].ToString();
                    string gradeName = dr["GradeName"].ToString();
                    dr["ClassName"] = gradeName + "--" + className;
                }
            }
            dgvStudentList.AutoGenerateColumns = false;//不允许自动添加列