efcore 级联删除

https://docs.microsoft.com/en-us/ef/core/saving/cascade-delete#required-relationships

 

 

Optional relationships

For optional relationships (nullable foreign key) it is possible to save a null foreign key value, which results in the following effects:

Behavior Name	Effect on dependent/child in memory	Effect on dependent/child in database
Cascade	Entities are deleted	Entities are deleted
ClientSetNull (Default)	Foreign key properties are set to null	None
SetNull	Foreign key properties are set to null	Foreign key properties are set to null
Restrict	None	None

Required relationships

For required relationships (non-nullable foreign key) it is not possible to save a null foreign key value, which results in the following effects:

Behavior Name	Effect on dependent/child in memory	Effect on dependent/child in database
Cascade (Default)	Entities are deleted	Entities are deleted
ClientSetNull	SaveChanges throws	None
SetNull	SaveChanges throws	SaveChanges throws
Restrict	None	None