If Foreign Key Not Exist Then Add Foreign Key Constraint(Or Drop a Foreign Key Constraint If Exist) without using Name?

Question

I am finding difficulties to creating a a query. Let say I have a Products and Brands table. I can add a foreign key using this command,

          ALTER TABLE Pr         


        

Answer 1

Try this:

IF NOT EXISTS (SELECT * FROM sys.objects o WHERE o.object_id = object_id(N'[dbo].[FK_Products_Brands]') AND OBJECTPROPERTY(o.object_id, N'IsForeignKey') = 1)
BEGIN
    ALTER TABLE [dbo].[Products] WITH CHECK ADD CONSTRAINT [FK_Products_Brands] FOREIGN KEY([BrandID]) REFERENCES [dbo].[Brands] ([Id])
END