Save function in c# windows form not completing due to a syntax error

Question

I am struggling to get this function working as it keeps flagging a syntax error within the INSERT INTO statement however the same code works on another page / form... can anyone help me out?

It seems to have this issue on another form now too however I can't see what is wrong with it...

private void btnAssign_Click(object sender, EventArgs e)
{
        string LocID = txtLocID.Text;
        string AssID = txtAssID.Text; // declaing instance names
        string StaID = txtID.Text;
        string Sku = txtSKU.Text;

        if (txtLocID.Text.Length < 1) // validating a text box
        {
            MessageBox.Show("Please Enter an Location ID");
        }
        else if (txtAssID.Text.Length < 1)
        {
            MessageBox.Show("Please Enter an Assignment ID");
        }
        else if (txtID.Text.Length < 1)
        {
            MessageBox.Show("Please Enter a Staff ID");
        }
        else if (txtSKU.Text.Length < 1)
        {
            MessageBox.Show("Please Enter a Product SKU");
        }
        else
        {
            try
            {
                int Loc;
                Cons.ConnectionString = ConnectionDetail.Warehouse;

                OleDbCommand cmds = new OleDbCommand();
                Cons.Open();
                cmds.CommandText = @"Insert into Assign (Location ID, Assign ID, Staff ID, SKU) VALUES (@LocID, @AssID, @StaID, @Sku)";
                cmds.Connection = Cons;

                cmds.Parameters.AddWithValue("LocID", LocID);
                cmds.Parameters.AddWithValue("AssID", AssID);
                cmds.Parameters.AddWithValue("StaID", StaID);
                cmds.Parameters.AddWithValue("Sku", Sku);

                Loc = cmds.ExecuteNonQuery();

                if (Loc > 0)
                    MessageBox.Show("Location has successfully been assigned a product and Saved");
            }
            catch (Exception err)
            {
                MessageBox.Show("error:" + Environment.NewLine + err.Message);
            }
            finally
            {
                if (Cons.State == ConnectionState.Open)
                    Cons.Close();
            }
        }
}

Answer 1

When your column names contains spaces you need to encapsulate them between square brackets to avoid confusing the database parser

cmds.CommandText = @"Insert into Assign ([Location ID], [Assign ID], 
                     [Staff ID], SKU) VALUES (@LocID, @AssID, @StaID, @Sku)";

I also suggest to avoid using AddWithValue because it could have unexpected side effects See Can we stop using AddWithValue already?

For example: I suppose that Location ID is a numeric field (probably an integer). AddWithValue doesn't know this. It sees a string passed as its parameter value. So the parameter is passed as a string. The Database engine need to convert it back to the type expected by the field and this conversion could be done correctly (as probably happens with a simple conversion from a string containing only digits to an integer) or could produce an invalid value as it happens a lot with DateTime values.
It is better to be explicit

 int locID;
 if(!Int32.TryParse(txtLocID.Text, out locID))
     MessageBox("Not a valid location number!");

 ......
 cmds.Parameters.Add("LocID", OleDbType.Integer).Value = locID;

Answer 2

INSERT into Assign([Location ID], [Assign ID] ...) values ...

在sql中，如果列/表/ ...名称包含空格或其他特殊字符，则必须将其放在方括号中。