An unhandled exception of type 'system.data.sqlclient.sqlexception' occurred in system.data.dll additional information: must declare the scalar variable "@name".

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C#

private void button2_Click(object sender, EventArgs e)
{
   string insert ="insert into [dbo].[Student_Info] values (@Name,@Address,@FatherName,@Class)";
   SqlCommand cmd = new SqlCommand(insert, con);
   SqlParameter[] prm = new SqlParameter[4];
   prm[0] = new SqlParameter("@Name", SqlDbType.VarChar);
   prm[0].Value = textBox9.Text;

   prm[1] = new SqlParameter("@Address", SqlDbType.VarChar);
   prm[1].Value = textBox8.Text;

   prm[2] = new SqlParameter("@FatherName", SqlDbType.VarChar);
   prm[2].Value = textBox7.Text;
   prm[3] = new SqlParameter("@Class", SqlDbType.VarChar);
   prm[3].Value = textBox6.Text;

   con.Open();
   cmd.ExecuteNonQuery();
   con.Close();
   MessageBox.Show("Inserted Data");
}

What I have tried:

please help me i have this erroe that want must be declare scalar variable

Posted 10-Aug-16 1:54am

Rohail Hanif

Updated 10-Aug-16 2:20am

Tomas Takac

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Tomas Takac · Answer 1 · 2016-08-10T02:19:00

Solution 1

You didn't add the parameters to the command:

C#

// prepare parameter array

cmd.Parameters.AddRange(prm);

// execute command

Alternatively you can add parameters directly to the collection:

C#

cmd.Parameters.Add("@Name", SqlDbType.VarChar).Value = textBox9.Text;

Posted 10-Aug-16 2:19am

Tomas Takac

Dave Kreskowiak · Answer 2 · 2016-08-10T02:20:00

For an INSERT statement without any column specifiers, SQL assumes that every column will have a value and all values are supplied in the exact order of the columns in the table. Using this method is bad practice. If you change the schema of the table, you break all of your code if it isn't updated properly.

You should be doing your inserts like

INSERT INTO dbo.Student_Info (Name, Address, FatherName, Class)
VALUES (@Name, @Address, @FatherName, @Class)

Note that I'm guessing at your column names and just assuming they match the names of your parameter values.

F-ES Sitecore · Answer 3 · 2016-08-10T02:20:00

Solution 3

You're simply creating SqlParameter objects, you're not attaching them to the command. After you create them attach them to the command's parameters collection

C#

cmd.Parameters.Add(prm[0]);

Posted 10-Aug-16 2:20am

F-ES Sitecore

Mehdi Gholam · Answer 4 · 2016-08-10T02:20:00

Solution 4

You add SqlParameter to a SqlCommand object, see :
http://www.dotnetperls.com/sqlparameter[^]
Lesson 06: Adding Parameters to Commands – C# Station[^]