C＃数据库列表框项删除

Question

I making a database and I can add names, but I can't remove please help me.

This is my code:

private void button2_Click(object sender, EventArgs e)
{
    using (connection = new SqlConnection(connectionString))
    using (SqlCommand cmds = new SqlCommand("DELETE FROM Recipe WHERE firstName = @user", connection))
    {
        connection.Open();
        cmds.Parameters.AddWithValue("@user", cmds);
        cmds.ExecuteNonQuery();

    }
    populateRecipe();
}

This is the error

An unhandled exception of type System.ArgumentException occurred in System.Data.dll Additional information: No mapping exists from object type System.Data.SqlClient.SqlCommand to a known managed provider native type.

Answer 1

Instead of passing the cmds itself to the AddWithValue method :

cmds.Parameters.AddWithValue("@user", cmds);

I suppose you should pass your actual uesrname :

cmds.Parameters.AddWithValue("@user", username);

Answer 2

You are passing the cmds variable as the value for the @user parameter which doesn't make sense because it's a SqlCommand object:

cmds.Parameters.AddWithValue("@user", cmds);

Don't you intend to pass the user's name that you want to delete instead?

cmds.Parameters.AddWithValue("@user", "Username");