unique-constraint

来源： https://stackoverflow.com/questions/1923826/django-how-do-i-validate-unique-together-from-within-the-model

来源： https://stackoverflow.com/questions/1923826/django-how-do-i-validate-unique-together-from-within-the-model

来源： https://stackoverflow.com/questions/1588984/how-to-make-no-duplicates-column-in-sql-server-2008

来源： https://stackoverflow.com/questions/1588984/how-to-make-no-duplicates-column-in-sql-server-2008

来源： https://stackoverflow.com/questions/1588984/how-to-make-no-duplicates-column-in-sql-server-2008

来源： https://stackoverflow.com/questions/20901565/unique-constraint-that-check-two-columns-in-mysql

来源： https://stackoverflow.com/questions/20901565/unique-constraint-that-check-two-columns-in-mysql

来源： https://stackoverflow.com/questions/64018097/unique-values-across-two-fields

问题 Context I have the models AppVersion , App & DeployApp . In the AppVersion model users can upload APK files to the filesystem. I am using a pre_save signal to prevent uploading APK files with the same version_code for a specific App like this: @receiver(pre_save, sender=AppVersion) def prevent_duplicate_version_code(sender, instance, **kwargs): qs = AppVersion.objects.filter(app_uuid=instance.app_uuid, version_code=instance.version_code) if qs.exists(): raise FileExistsError("Version code has

问题 I have an entity which has @OneToMany private ownership of a collection of another entities. That other entity has some unique constraints over different set of columns. The problem arises when I want to update the main entity (together with changed child entities). EclipseLink does insert before delete, so sometimes, an insertion violates the constraint and throws an exception. Is there a way to force the deletion of child entities before inserting their updated counterparts? 回答1: I know, I