How can I make the primary key value the same the foreign key in a different table?

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C#

ASP.NET

SQL

Hi, I currently have a ASP.NET web application that captures the users input and puts it into a database.

I have two tables 'Stock_Take' and 'Stock_Take_Item', Stock_Take stores the information of the user who submitted the values and the date of the stock take and the stock_take_item stores the information of the Item ID, Item Description, and the Quantity regarding each item.

The primary key of Stock_Take is StockTakeIDNew and auto increments using 'Identity'and is a foreign key in the Stock_Take_Item table.

As I insert all the information from the Stock Take (on a click of a button) i only insert the username and date into Stock_Take and the primary key auto increments. However this does not affect the foreign key in the Stock_Take_Item table, therefore i cannot relate the two tables.

Any idea how i go about this?

Here's my C# code with the SQL Inserts included:

protected void btnSubmit_Click(object sender, EventArgs e)
       {
       string query = "insert into Stock_Take_Item(ItemID, BarQuantity, StorageQuantity) values(@ID, @BAR, @STORAGE); insert into Stock_Take(Username, StockDate)" +
           " values(@Username, GetDate())";
       SqlConnection con = new SqlConnection(connectionString);
       SqlCommand cmd = new SqlCommand(query, con);
       con.Open();

       foreach (GridViewRow row in gvStockTake.Rows)
       {
           Label ID = row.FindControl("itemId") as Label;
           TextBox BAR = row.FindControl("txtBar") as TextBox;
           TextBox STORAGE = row.FindControl("txtStorage") as TextBox;
           cmd.Parameters.Clear();
           cmd.Parameters.Add("@ID", SqlDbType.VarChar).Value = ID.Text;
           cmd.Parameters.Add("@BAR", SqlDbType.Int).Value = BAR.Text;
           cmd.Parameters.Add("@STORAGE", SqlDbType.Int).Value = STORAGE.Text;

       }
       cmd.Parameters.AddWithValue("@Username", Session["username"]);
       cmd.ExecuteNonQuery(); //query execution
       con.Close();
       Response.Write("Successfully inserted stock take items.");
   }

I'm still learning ASP.NET C# and SQL as i go, so any recommendations are more than appreciated!!

What I have tried:

I've tried to research this but could not find the right result.