Question

I have a table with a nullable FK field. I made it nullablle to avoid changing the loader.

In order to achieve (Advertisers)* 1(Currencies), I wrote a simple trigger:

ALTER TRIGGER InsertedAdvertisersDefaultCurrency
ON dbo.Advertisers
FOR INSERT
AS
    UPDATE Advertisers
    SET Currency_Id=(SELECT TOP 1 Id FROM Currencies WHERE Name='USD')
    WHERE Currency_Id=NULL

My question is basically about how I am checking the whole table for null rows on every insert.

I feel like I should be using the inserted table (?)

Here’s the table:

CREATE TABLE [dbo].[Advertisers](
    [Id] [int] IDENTITY(1,1) NOT NULL,
    [Name] [nvarchar](max) NOT NULL,
    [Currency_Id] [int] NULL,
 CONSTRAINT [PK_Advertisers] PRIMARY KEY CLUSTERED 
(
    [Id] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[Advertisers]  WITH CHECK ADD  CONSTRAINT [FK_CurrencyAdvertiser1] FOREIGN KEY([Currency_Id])
REFERENCES [dbo].[Currencies] ([Id])
GO
ALTER TABLE [dbo].[Advertisers] CHECK CONSTRAINT [FK_CurrencyAdvertiser1]
GO

Answer 1

Yes, you should just update the insertd records:

UPDATE Advertisers
SET Currency_Id=(SELECT TOP 1 Id FROM Currencies WHERE Name='USD')
WHERE Id in (select Id from inserted)

Or you may use a default value in that field

ALTER TABLE [dbo].[Advertisers] ADD  CONSTRAINT [DF_Advertisers_Currency_Id]  DEFAULT ((101)) FOR [Currency_Id]
GO

Where 101 is the USD id