1. ON DELETE CASCADE：当参照的主表记录被删除时，从表中所有匹配的记录也会被删除。例如，如果我们有一个订单表和一个用户表，用户表中用户ID作为主键，订单表中有一个用户ID的外键。如果一个用户被删除了，并且外键约束设置为ON DELETE CASCADE，那么该用户的所有订单也将被自动删除。2. ON DELETE...
SET(): 自定义一个值,该值当然只能是对应的实体了 3、补充说明:关于SET()的使用 **官方案例**defget_sentinel_user():returnget_user_model().objects.get_or_create(username='deleted')[0]classMyModel(models.Model): user = models.ForeignKey( settings.AUTH_USER_MODEL, on_delete=models.SET(get_s...
owner=models.ForeignKey(UserProfile,on_delete=models.CASCADE) --在老版本这个参数(models.CASCADE)是默认值 参数说明: on_delete有CASCADE、PROTECT、SET_NULL、SET_DEFAULT、SET()五个可选择的值 CASCADE:此值设置,是级联删除。 PROTECT:此值设置,是会报完整性错误。 SET_NULL:此值设置,会把外键设置为null,...
DELETE的Default ON是指在数据库中执行DELETE操作时,如果没有指定WHERE子句,即删除所有记录时的默认行为。 默认情况下,DELETE操作会删除表中的所有记录,即删除整个表的数据...
先看On Delete属性,可能取值如上图为:No Action, Cascade,Set Null, Restrict属性。 当取值为No Action或者Restrict时,则当在父表(即外键的来源表)中删除对应记录时,首先检查该记录是否有对应外键,如果有则不允许删除。 当取值为Cascade时,则当在父表(即外键的来源表)中删除对应记录时,首先检查该记录是否有对应...
-delete /Groups/admin GroupMembers <GeneratedUID>To find the GeneratedUID of an account:dscl . -read /Users/<username> GeneratedUIDSee also this post for more information about how macOS determines group membership.FirmwareYou should check that firmware security settings are set to Full Security ...
set_on_delete(collector,field,sub_objs,using):collector.add_field_update(field,value(),sub_objs)else:defset_on_delete(collector,field,sub_objs,using):collector.add_field_update(field,value,sub_objs)set_on_delete.deconstruct=lambda:('django.db.models.SET',(value,),{})returnset_on_delete...
dbAdd()and its higher level counterpartsetKey()create a new key in a Redis database. dbDelete()removes a key and its associated value. emptyData()removes an entire single database or all the databases defined. The rest of the file implements the generic commands exposed to the client. ...
Delete an unmanaged solution If you delete an unmanaged solution, you just delete the group used to contain references to solution components. The solution components in an unmanaged solution remain in the system but they are no longer associated with the unmanaged solution you delete. ...
public TimeSpan AutoDeleteOnIdle { get; set; } Property Value TimeSpan Remarks The minimum duration is 5 minutes. Default value is MaxValue. Applies to 產品版本 Azure SDK for .NET Latest, Preview 在GitHub 上與我們共同作業 您可以在 GitHub 上找到此內容的來源,在其中建立和檢閱問...