SQL - INSERT with Scope_Identity() - getting the record id

Question

I have an ASP.NET page written in VB.NET that gets the items into a GridView by using a SELECT statement with INNER JOIN and also allo

Answer 1

ItemId = AddNewItemSQL.ExecuteScalar()

        AddNewItemSQL.ExecuteNonQuery()

These two rows next to each other will execute the command twice. You should remove the second one - ExecuteNonQuery. This will have your data inserted twice in the Items - two same rows but with different IDs.

Since you only retrieve ItemID from the first row, that one should be inserted in project_items, but the other one that was last inserted in items will have no matching row.

Also - complete section from beginning of button click method up before Dim AddNewItemComm As String - where you open and close DataReader and do nothing with it seems completely unnecessary.

Answer 2

Why are you doing this in multiple statements in the first place? Why not:

INSERT dbo.Items (item_name,  item_cost, item_code) 
  OUTPUT inserted.ItemID, @ProjectID, @ItemQuantity 
  INTO dbo.project_items(item_id, project_id, item_quantity)
VALUES (@ItemName, @ItemCost, @ItemCode);

Now you only have to call one ExecuteNonQuery() and your app doesn't have to care about the actually SCOPE_IDENTITY() value generated. (You can still retrieve SCOPE_IDENTITY() if you want, of course, using ExecuteScalar - but as Nenad rightly points out, pick one instead of calling both.)

Since we now know that there is an explicit foreign key here, we can still reduce your C# code to one call even if we can't use the OUTPUT clause.

DECLARE @i INT;

INSERT dbo.Items (item_name,  item_cost, item_code) 
  SELECT @ItemName, @ItemCost, @ItemCode;

SELECT @i = SCOPE_IDENTITY();

INSERT dbo.project_items(item_id, project_id, item_quantity)
  SELECT @i, @ProjectID, @ItemQuantity 

SELECT @i; -- if necessary

Would be even cleaner to put this into a stored procedure.