Example of some custom code to clear data from a table with a self-referencing FK constraint

blog-001-custom.sql

DELETE FROM ...

IF  EXISTS (SELECT * FROM sys.foreign_keys WHERE object_id = OBJECT_ID(N'[dbo].[FK_Customer_Customer_MergedToCustomerId]') AND parent_object_id = OBJECT_ID(N'[dbo].[Customer]'))
ALTER TABLE [dbo].[Customer] DROP CONSTRAINT [FK_Customer_Customer_MergedToCustomerId]

DELETE FROM [dbo].[Customer]

ALTER TABLE [dbo].[Customer]  WITH CHECK ADD  CONSTRAINT [FK_Customer_Customer_MergedToCustomerId] FOREIGN KEY([MergedToCustomerId])
REFERENCES [dbo].[Customer] ([CustomerId])
ALTER TABLE [dbo].[Customer] CHECK CONSTRAINT [FK_Customer_Customer_MergedToCustomerId]

DELETE FROM ...