Entity Framework The ALTER TABLE statement conflicted with the FOREIGN KEY constraint

Question

On updating database in Entity Framework , Code first Migration, I am getting this error:

The ALTER TABLE statement conflicted with the FOREIGN KEY constr

Answer 1

This error is telling you that you are violating the foreign key constraint. To resolve you have a few solutions

1. Fix your data - Somewhere there are records in the Clients table that have a MedicalGroupId that does not exist in the in the MedicalGroups table. Write a query to find out what IDs do not exist in the MedicalGroups table and manually fix the data yourself.
2. Remove the foreign key constraint - Obviously if you remove the foreign key constraint you will no longer be bothered by this message. Unfortunately the database will no longer enforce this relationship and might make this problem worse in the future.
3. Create constraint using WITH NOCHECK - You can create your foreign key constraint using the WITH NOCHECK option. This option tells SQL Server to not apply this constraint to existing data. SQL Server WILL check this constraint in any future INSERTS/UPDATES/DELETES.