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ADO.NET 七(一个例子)

时间:2019-08-21 15:14:01      阅读:116      评论:0      收藏:0      [点我收藏+]

标签:command   button   failed   学分   delete   update   通过   编号   items   

  通过一个完整的实例实现课程信息管理功能的操作,包括查询、修改、删除课程信息等操作。

1) 创建课程信息表

create table StuCourse
(
    id int primary key identity(1,1),
    name varchar(20),
    credit numeric(3,1),
    remark varchar(50)
);

  INSERT INTO StuCourse (name,credit,remark) VALUES (‘English‘,3.00,‘Good Good Study‘);
  INSERT INTO StuCourse (name,credit,remark) VALUES (‘Math‘,2.56,‘Good Good Study, Day‘);
  INSERT INTO StuCourse (name,credit,remark) VALUES (‘Chinese‘,4.04,‘Good Good Study, Day Day‘);
  INSERT INTO StuCourse (name,credit,remark) VALUES (‘English1‘,3.00,‘Good Good Study‘);
  INSERT INTO StuCourse (name,credit,remark) VALUES (‘Math1‘,2.56,‘Good Good Study, Day‘);
  INSERT INTO StuCourse (name,credit,remark) VALUES (‘Chinese1‘,4.04,‘Good Good Study, Day Day‘);

2) 课程信息管理界面的设计

  DataGridView 控件用于显示课程信息,并提供了根据课程名称查找课程信息、修改以及删除的功能,另外提供增加课程功能(暂无)。

  技术图片

   技术图片

 

3) 具体代码(不细分了)

  实体类:

  /// <summary>
  /// 课程实体类(实际应创建一实体类的项目,里面可能有多个实体类
  /// </summary>
  public class Entities
  {
    /// <summary>
    /// 编号(数据库中的自增主键)
    /// </summary>
    public int ID { get; set; }
    /// <summary>
    /// 课程名称
    /// </summary>
    public string Name { get; set; }
    /// <summary>
    /// 课程学分
    /// </summary>
    public float Credit { get; set; }
    /// <summary>
    /// 备注
    /// </summary>
    public string Remark { get; set; }
  }

 

  业务层数据层:

  /// <summary>
  /// 课程相关处理类(实际应将业务逻辑层BLL与数据库层DAL分开,各自创建一个项目
  /// </summary>
  public class CourseInfo
  {
    static string conString = "Data Source=.;Initial Catalog=TestDB;Integrated Security=True;";

    /// <summary>
    /// 返回所有课程信息
    /// </summary>
    /// <returns> List<Entities></returns>
    public static List<Entities> GetAllCourseInfo()
    {
      SqlDataReader reader = null;
      try
      {
        List<Entities> entities = new List<Entities>();
        string sqlStr = "SELECT * FROM StuCourse";
        using (SqlConnection con = new SqlConnection(conString))
        {
          con.Open();
          SqlCommand cmd = new SqlCommand(sqlStr, con);
          reader = cmd.ExecuteReader();
          while (reader.Read())
          {
            int id = reader["id"] == DBNull.Value ? -1 : Convert.ToInt32(reader["id"]);
            string name = reader["name"] == DBNull.Value ? "" : reader["name"].ToString();
            float credit = reader["credit"] == DBNull.Value ? 0f : Convert.ToSingle(reader["credit"]);
            string remark = reader["remark"] == DBNull.Value ? "" : reader["remark"].ToString();

            Entities entity = new Entities()
            {
              ID = id,
              Name = name,
              Credit = credit,
              Remark = remark
            };
            entities.Add(entity);
          }
        }
        return entities;
      }
      catch (Exception)
      {
        //打印log
        throw;
      }
      finally
      {
        if (reader != null)
        {
          reader.Close();
        }
      }
    }

/// <summary>
/// 返回查找的课程信息,模糊查询
/// </summary>
/// <param name="courseName"></param>
/// <returns>List<Entities></returns>
public static List<Entities> GetTheCourseInfo(string courseName)
{
  SqlDataReader reader = null;
  try
  {
    string sqlStr = "";
    List <Entities> entities = new List<Entities>();
    if (courseName == "All Course")
      sqlStr = $"SELECT * FROM StuCourse";
    else
      sqlStr = $"SELECT * FROM StuCourse WHERE name like ‘%{courseName}%‘";
    using (SqlConnection con = new SqlConnection(conString))
    {
      con.Open();
      SqlCommand cmd = new SqlCommand(sqlStr, con);
      reader = cmd.ExecuteReader();
      while (reader.Read())
      {
        int id = reader["id"] == DBNull.Value ? -1 : Convert.ToInt32(reader["id"]);
        string name = reader["name"] == DBNull.Value ? "" : reader["name"].ToString();
        float credit = reader["credit"] == DBNull.Value ? 0f : Convert.ToSingle(reader["credit"]);
        string remark = reader["remark"] == DBNull.Value ? "" : reader["remark"].ToString();

        Entities entity = new Entities()
        {
          ID = id,
          Name = name,
          Credit = credit,
          Remark = remark
        };
        entities.Add(entity);
      }
    }
    return entities;
  }
  catch (Exception)
  {
    //打印log
    throw;
  }
  finally
  {
    if (reader != null)
    {
      reader.Close();
    }
  }
}


/// <summary>
/// 删除
/// </summary>
/// <param name="courseID"></param>
/// <returns>int</returns>
public static int DeleteTheCourseInfo(int courseID)
{
  try
  {
    int res = -1;
    List<Entities> entities = new List<Entities>();
    string sqlStr = $"DELETE FROM StuCourse WHERE id = {courseID}";
    using (SqlConnection con = new SqlConnection(conString))
    {
      con.Open();
      SqlCommand cmd = new SqlCommand(sqlStr, con);
      res = cmd.ExecuteNonQuery();
    }

        return res;
      }  
      catch (Exception)
      {
        //打印log
        throw;
      }
    }

/// <summary>
/// 更新
/// </summary>
/// <param name="entity"></param>
/// <returns>int</returns>
public static int UpdateTheCourseInfo(Entities entity)
{
  try
  {
    int res = -1;
    string sqlStr = $@"UPDATE StuCourse SET name = N‘{entity.Name}‘,
    credit = {entity.Credit}, remark = N‘{entity.Remark}‘ WHERE id = {entity.ID}";
    using (SqlConnection con = new SqlConnection(conString))
    {
      con.Open();
      SqlCommand cmd = new SqlCommand(sqlStr, con);
      res = cmd.ExecuteNonQuery();
    }

        return res;
      }
      catch (Exception)
      {
        //打印log
        throw;
      }
    }

/// <summary>
/// 增加
/// </summary>
/// <param name="entity"></param>
/// <returns>int</returns>
public static int AddTheCourseInfo(Entities entity)
{
  try
  {
    int res = -1;
    string sqlStr = $@"INSERT INTO StuCourse (name,credit,remark) VALUES
    (‘{entity.Name}‘, {entity.Credit}, ‘{entity.Remark}‘)";
    using (SqlConnection con = new SqlConnection(conString))
    {
      con.Open();
      SqlCommand cmd = new SqlCommand(sqlStr, con);
      res = cmd.ExecuteNonQuery();
    }

        return res;
      }
      catch (Exception)
      {
        //打印log
        throw;
      }
    }

  }

 

  界面代码:

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

private void Form1_Load(object sender, EventArgs e)
{
  Init();
}

private void Init()
{
  List<Entities> allCourseInfo = CourseInfo.GetAllCourseInfo();
  dgvCourseInfo.DataSource = allCourseInfo;
  cbCourseName.Items.Add("All Course");
  for (int i = 0; i < allCourseInfo.Count; i++)
  {
    cbCourseName.Items.Add(allCourseInfo[i].Name);
  }
  if (cbCourseName.Items.Count > 0)
  {
    cbCourseName.SelectedIndex = 0;
  }
  //dgvCourseInfo.SelectionMode = DataGridViewSelectionMode.FullRowSelect;

      //dgvCourseInfo.Columns[0].HeaderText = "id";
      //dgvCourseInfo.Columns[1].HeaderText = "名称";
    }

//private void cbCourseName_SelectedIndexChanged(object sender, EventArgs e)
//{
  // if (!string.IsNullOrWhiteSpace(cbCourseName.SelectedItem.ToString()))
  // {
    // btnSearch_Click(sender, e);
  // }
//}

 

//查询
private void btnSearch_Click(object sender, EventArgs e)
{
  List<Entities> theCourseInfo = CourseInfo.GetTheCourseInfo(cbCourseName.SelectedItem.ToString().Trim());
  if (theCourseInfo.Count > 0)
  {
    dgvCourseInfo.DataSource = null;
    dgvCourseInfo.DataSource = theCourseInfo;
    MessageBox.Show(theCourseInfo.Count.ToString() + "条数据", "Tips", MessageBoxButtons.OK,               MessageBoxIcon.Information);
  }
  else
  {
    dgvCourseInfo.DataSource = null;
    MessageBox.Show("No Data","Tips", MessageBoxButtons.OK,MessageBoxIcon.Information);
  }
}

 

//删除
private void btnDelete_Click(object sender, EventArgs e)
{
  if (dgvCourseInfo.DataSource == null)
  {
    MessageBox.Show("Search first", "Tips", MessageBoxButtons.OK, MessageBoxIcon.Information);
    return;
  }
  dgvCourseInfo.MultiSelect = false;
  DataGridViewSelectedRowCollection src = dgvCourseInfo.SelectedRows;
  if (src.Count == 0)
  {
    MessageBox.Show("Choose first", "Tips", MessageBoxButtons.OK, MessageBoxIcon.Information);
    return;
  }
  int id = Convert.ToInt32(src[0].Cells[0].Value);
  int res = CourseInfo.DeleteTheCourseInfo(id);

      if (res > 0)
      {
        List<Entities> allCourseInfo = CourseInfo.GetAllCourseInfo();
        dgvCourseInfo.DataSource = allCourseInfo;
      }
      else
      {
        MessageBox.Show("Delete failed", "Tips", MessageBoxButtons.OK, MessageBoxIcon.Information);
        return;
      }
    }

 

//更新
private void btnUpdate_Click(object sender, EventArgs e)
{
  if (dgvCourseInfo.DataSource == null)
  {
    MessageBox.Show("Search first", "Tips", MessageBoxButtons.OK, MessageBoxIcon.Information);
    return;
  }
  dgvCourseInfo.MultiSelect = false;
  DataGridViewSelectedRowCollection src = dgvCourseInfo.SelectedRows;
  if (src.Count == 0)
  {
    MessageBox.Show("Choose first", "Tips", MessageBoxButtons.OK, MessageBoxIcon.Information);
    return;
  }
  int id = Convert.ToInt32(src[0].Cells[0].Value);
  string name = src[0].Cells[1].Value.ToString();
  float credit = Convert.ToSingle(src[0].Cells[2].Value);
  string remark = src[0].Cells[3].Value.ToString();
  int res = CourseInfo.UpdateTheCourseInfo(new Entities() {
    ID=id,
    Name=name,
    Credit=credit,
    Remark=remark
  });

      if (res > 0)
      {
        List<Entities> allCourseInfo = CourseInfo.GetAllCourseInfo();
        dgvCourseInfo.DataSource = allCourseInfo;
      }
      else
      {
        MessageBox.Show("Update failed", "Tips", MessageBoxButtons.OK, MessageBoxIcon.Information);
        return;
      }
    }

  }

 

  不合理的地方有待改进。

  参考:http://c.biancheng.net/view/3040.html

ADO.NET 七(一个例子)

标签:command   button   failed   学分   delete   update   通过   编号   items   

原文地址:https://www.cnblogs.com/lu-yuan/p/11388818.html

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