插入语句 [英] Insert Statement

问题描述

嗨

我试图在数据库中插入值，但出现以下错误:没有为一个或多个必需参数提供值"

//下面是我的代码

Hi

Im trying to insert values in a database but i get the following error:"No value given for one or more required parameters"

//Below is my code

protected void btnAddCourse_Click(object sender, EventArgs e)
   {
       //try
       //{
           string connString = ConfigurationManager.ConnectionStrings["courses"].ConnectionString;
           // set up and open connection
           dbConn = new OleDbConnection(connString);
           dbConn.Open();
           string updateSql = "UPDATE Courses " + "SET coursePrice = @price, StartDate=@date, Duration=@duration, Venue=@venue " + "WHERE Venue = @courseNo";
           dbCmd = new OleDbCommand(updateSql, dbConn);

           dbCmd.Parameters.Add("@price", OleDbType.VarChar, 20, "coursePrice");
           dbCmd.Parameters.Add("@date", OleDbType.VarChar, 20, " StartDate");
           dbCmd.Parameters.Add("@duration", OleDbType.VarChar, 10, "Duration");
           dbCmd.Parameters.Add("@venue", OleDbType.VarChar, 20, " Venue");

           dbCmd.Parameters["@price"].Value = txtPrice.Text;
           dbCmd.Parameters["@date"].Value = txtDate.Text;

           dbCmd.Parameters["@duration"].Value = txtDuration.Text;
           dbCmd.Parameters["@venue"].Value = txtVenue.Text;

           dbCmd.ExecuteNonQuery();
           MessageBox.Show("Added");

       //}
       //catch(OleDbException ex)
       //{
       //    MessageBox.Show(ex.Message);
       //}

   }

推荐答案

string updateSql = "UPDATE Courses " + "SET coursePrice = @price, StartDate=@date, Duration=@duration, Venue=@venue " + "WHERE Venue = @courseNo";

请注意最后一个参数:"@ courseNo".
您在哪里设置?你把所有其他的都设置好了！

顺便说一句:UPDATE命令不添加任何记录-它修改现有记录.因此，您使用的是错误的SQL命令，而是要使用INSERT，或者您的方法名以及消息框是错误的！

Note the final parameter: "@courseNo".
Where do you set it? You set all the others!

BTW: An UPDATE command does not add any records - it modifies an existing one. So you are either using the wrong SQL command and want INSERT instead, or your method name is wrong, as well as your message box!

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