选择datetimepicker值时，Datagridview显示为空白 [英] Datagridview show blank when choosing datetimepicker value

问题描述

大家好，



当我选择From Date和Todate from datetimepicker来显示datagridview中的数据时datagridview显示我的null数据，代码写入按钮点击evet



我的尝试：

Hi all,

When i choose From Date and Todate from datetimepicker to show data in datagridview at that time datagridview show me null data , code is written button click evet

What I have tried:

 DateTime startT = new DateTime();
                DateTime endT = new DateTime();
                startT = dateTimePicker1.Value.Date;
                endT = dateTimePicker2.Value.Date;
                if (startT.Date > endT.Date)
                {
                    MessageBox.Show("To Date Cannot be greater than Start Date");
                }
                else
                {
                    string connetionString = null;
                    connetionString = ConfigurationManager.ConnectionStrings["AccessConnectionString"].ConnectionString;
                    con.ConnectionString = connetionString;

                    DataSet ds = new DataSet();
                    string sql = "SELECT Medicine_name,sum(Medicine_count) as Medicine_count,To_Date from Medicine_count where [To_Date] Between #" + startT.ToString("dd'/'MM'/'yyyy") + "#And #" + endT.ToString("dd'/'MM'/'yyyy") + "#group by Medicine_name,Medicine_count,To_Date";
                    OleDbConnection connection = new OleDbConnection(connetionString);
                    OleDbDataAdapter dataadapter = new OleDbDataAdapter(sql, connection);
                    ds = new DataSet();
                    connection.Open();
                    dataadapter.Fill(ds);
                    connection.Close();
                    dataGridView1.DataSource = ds;
                    temp = true;
}

推荐答案

停止这样做......永远不要连接字符串来构建SQL命令。它让您对意外或故意的SQL注入攻击持开放态度，这可能会破坏您的整个数据库。请改用参数化查询。

您的问题可能会在同一时间消失。

Stop doing that... Never concatenate strings to build a SQL command. It leaves you wide open to accidental or deliberate SQL Injection attack which can destroy your entire database. Use Parametrized queries instead.
The chances are your problem will disappear at the same time.

string sql = "SELECT Medicine_name, SUM(Medicine_count) AS Medicine_count, To_Date FROM Medicine_count WHERE [To_Date] BETWEEN ? AND ? GROUP BY Medicine_name,Medicine_count,To_Date";
OleDbConnection connection = new OleDbConnection(connetionString);
OleDbDataAdapter dataadapter = new OleDbDataAdapter(sql, connection);
dataadapter.SelectCommand.Parameters.AddWithValue("?", startT);
dataadapter.SelectCommand.Parameters.AddWithValue("?", endT);

并且SELECT可能无法达到您想要的效果：GROUP BY会将列表中的每一列视为生成新列的原因行： SQL GROUP By和the列'名称'在选择列表中无效，因为......错误 [ ^ ]

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