填充C＃WinForms DataGridview

Question

I have a DataGridview on my form, as below, which the users can enter rows of data. As you can see one of the columns is a Combobox column.

When a user clicks the save button on the form, the entries they have added to the grid are saved into a table in the database.

What I need it to do once this is done, is when the form is opened next time, any entries where the Location is "Stock" are still sitting in the grid. I have tried the below code but just get the below issue.

        SqlConnection con = new SqlConnection(ConString);
        con.Open();
        SqlCommand cmd1 = new SqlCommand("SELECT ProductID, Location FROM ProductLoc WHERE Location LIKE 'Stock'", con);
        cmd1.CommandType = CommandType.Text;
        DataTable dt = new DataTable();
        SqlDataReader re = cmd1.ExecuteReader();
        dt.Load(re);
        ProductLocGrid.DataSource = dt;

Result when the form loads:

As you can see it adds the data from the SELECT statement as two new columns, instead of populating the existing columns with the data. I need it to load the form with the existing data populated, and retaining the ability to add new rows and also change the Location column of the existing data. Above it's loading the existing Location as a text field, instead of choosing that option from the combobox column.

I read somewhere that the columns in the database and the columns in the datagridview need to be the same - they are.

I'm completely stumped, and this is the last bit of work I need to do on this project and I'm finally done (only taken 6 months of different people getting involved and requesting changes - it's nothing like the original spec!).

Any help would be gratefully received.

Many thanks in advance.

UPDATE: Following a suggestion from Fabio in the comments, i added the line

ProductLocGrid.AutoGenerateColumns = false;

When i load the form, the grid now looks like this:

As you can see, the columns are no longer duplicating, however the data isn't being populated either.

Answer 1

Many thanks to Fabio's suggestion to add

DataGridView.AutoGenerateColumns = false;

I added this and at first it didn't work, however when I found I had done a typo and corrected my column name it worked perfectly.