我在数据库中遇到了一个问题，但我不知道为什么 [英] I have facing a issue in database but I dont know why

问题描述

Hello Guys, am facing a little issue i got an error no value given for one or more required parameters.

What I have tried:

DataSet dsa = new DataSet();
            DataTable dt = new DataTable();
            dsa.Tables.Add(dt);
            OleDbDataAdapter da = new OleDbDataAdapter();
            da = new OleDbDataAdapter("SELECT [Flavours],COUNT(Flavours)As[asdf] From [Total] Where [Dates] >= #" + dateTimePicker1.Value.ToString("dd/MM/yyyy") + "# AND [Dates] <= #" + dateTimePicker2.Value.ToString("dd/MM/yyyy") + "# Group By [Flavours]", VCON);
            da.Fill(dt);
            dataGridView1.DataSource = dt;
            VCON.Close();

推荐答案

停止使用字符串连接传递值 - 使用参数化查询代替：

Stop using string concatenation to pass values - use a parameterised query instead:

OleDbDataAdapter da = new OleDbDataAdapter();
da = new OleDbDataAdapter("SELECT [Flavours],COUNT(Flavours)As[asdf] From [Total] Where [Dates] BETWEEN ? AND  ? Group By [Flavours]", VCON);
da.SelectCommand.Parameters.AddWithValue("?", dateTimePicker1.Value);
da.SelectCommand.Parameters.AddWithValue("?", dateTimePicker2.Value);
da.Fill(dt);

如果您习惯使用字符串连接，请注意您的数据库存在SQL注入的风险，其中用户是只需键入文本框即可销毁它： xkcd：对妈妈的利用 [ ^ ]

始终使用参数化查询。

If you are habitually using string concatenation, then be aware that your database is at risk for SQL Injection, where a user can destroy it just by typing in text boxes: xkcd: Exploits of a Mom[^]
Always use parameterised queries.

包含查询的字符串不正确。尝试通过参数传递值。

Hi,
Your string containing query is not correct. Try pass values through parameters.

OleDbDataAdapter da = new OleDbDataAdapter（）;

da = new OleDbDataAdapter（SELECT [Flavors]，COUNT（Flavors）As [ asdf]从[Total] Where [Dates] BETWEEN Columnname1和Columnname2 Group by [Flavors]，VCON）;

da.SelectCommand.Parameters.AddWithValue（@ Columnname1，dateTimePicker1.Value）;

da.SelectCommand.Parameters.AddWithValue（@ Columnname1，dateTimePicker2.Value）;

da.Fill（dt）;



其中@Columnname / @Parametername与数据库中的相同。

您也可以将dateTimePicker1.Value转换为数据库端所需的字符串或日期时间

OleDbDataAdapter da = new OleDbDataAdapter();
da = new OleDbDataAdapter("SELECT [Flavours],COUNT(Flavours)As[asdf] From [Total] Where [Dates] BETWEEN Columnname1 AND Columnname2 Group By [Flavours]", VCON);
da.SelectCommand.Parameters.AddWithValue("@Columnname1", dateTimePicker1.Value);
da.SelectCommand.Parameters.AddWithValue("@Columnname1", dateTimePicker2.Value);
da.Fill(dt);

Where @Columnname / @Parametername is same as in database.
also you can convert dateTimePicker1.Value to string or datetime as required in database side

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