c#中的数据网格访问

本文关键字：网格 访问 数据网 数据 | 更新日期: 2023-09-27 18:02:07

我是c#和Database链接的新手，这就是为什么不能通过搜索stackoverflow的旧帖子来获得这个

代码

private void issueDetails()
    {
        string connectionPath = @"Data Source=Data'libraryData.dat;Version=3;New=False;Compress=True";
        using (SQLiteConnection connection = new SQLiteConnection(connectionPath))
        {
            SQLiteCommand command = connection.CreateCommand();
            connection.Open();
            string query = "SELECT bookno as 'Book No.',studentId as 'Student ID',  title as 'Title', author as 'Author', description as 'Description', issuedDate as 'Issued Date', dueDate as 'Due Date' FROM issuedBooks";
            command.CommandText = query;
            command.ExecuteNonQuery();
            SQLiteDataAdapter da = new SQLiteDataAdapter(command);
            DataSet ds = new DataSet();
            da.Fill(ds, "issuedBooks");
            dataGridView1.DataSource = ds.Tables["issuedBooks"];
            dataGridView1.Sort(dataGridView1.Columns["Student ID"], ListSortDirection.Ascending);
            dataGridView1.ReadOnly = true;
            connection.Close();
        }
    }

我像上面一样使用了一些图书馆图书的详细信息，如issuedDate和dueDate，现在我想突出显示一个超过dueDate的特定单元格。

private void dataGridView1_CellFormatting(object sender, DataGridViewCellFormattingEventArgs e)
    {
        Color c = Color.Black;
        if (e.ColumnIndex == 6)
        {
            if (isLate(Convert.ToString(e.Value)))
            {
                c = Color.Red;
                count++;
                Console.WriteLine(count);
            }
        }
        e.CellStyle.ForeColor = c;
    }
    public string toInd(string date)
    {
        DateTimeFormatInfo fmt = new CultureInfo("fr-fr").DateTimeFormat;
        string dateString;
        DateTimeOffset offsetDate, dateig;
        string ret = DateTime.Now.ToShortDateString();
        dateString = date;
        bool ws = DateTimeOffset.TryParse(dateString, fmt, DateTimeStyles.None, out dateig);
        if (ws)
        {
            offsetDate = DateTimeOffset.Parse(dateString, fmt);
            ret = offsetDate.Date.ToShortDateString();
            return ret;
        }
        return ret;
    }
    private bool isLate(string nowS)
    {
        DateTime dueDate = Convert.ToDateTime(toInd(nowS));
        DateTime now;
        string present = DateTime.Now.ToShortDateString();
        now = Convert.ToDateTime(present);
        //Console.WriteLine(toInd(nowS));
        int a = dueDate.CompareTo(now);
        if (a >= 0)
            return false;
        else return true;
    }

但是如果使用if (isLate(Convert.ToString(e.Value))) { c = Color.Red; count++; Console.WriteLine(count); }这对于过期的书籍数量，'count'值增加4次，即使在我的数据库中只有两本书过期，因为这如果在数据绑定时阻塞访问2次，并且在排序时再次两次，我如何才能只获得过期书籍的数量

c#中的数据网格访问

实际上dataGridView1_CellFormatting是在每个单元格事件上触发的，包括如果您排序，或者甚至如果您将鼠标悬停在单元格上。在性能方面非常昂贵。

相反，您可以使用dgv上的RowsAdded事件，该事件仅在添加时触发一次:

    private void dataGridView1_RowsAdded(object sender, DataGridViewRowsAddedEventArgs e)
    {
        if (isLate(dataGridView1[6, e.RowIndex].Value.ToString()))
        {
            dataGridView1[0, e.RowIndex].Style.ForeColor = Color.Red;
            count++;
        }
    }

答案

private void UpdateDataGridViewColor()
    {
        if (calledMethod == 2)
        {
            for (int i = 0; i < dataGridView1.RowCount; i++)
            {
                int j = 6;
                DataGridViewCellStyle CellStyle = new DataGridViewCellStyle();
                CellStyle.ForeColor = Color.Red;
                if (isLate(dataGridView1[j, i].Value.ToString()))
                {
                    dataGridView1[j, i].Style = CellStyle;
                }
            }
        }
    }
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