ON DELETE RESTRICT是一种外键约束,它规定如果尝试删除被引用表中的数据行,而这些数据行在引用表中被其他数据行所引用,那么删除操作将被阻止。简而言之,它防止删除那些在其他表中还有引用的数据行。 描述"ON DELETE RESTRICT"在PostgreSQL中的用途: 在PostgreSQL中,ON DELETE RESTRICT用于维护数据的一致性和完整性。
'附件文件名称'; comment on column t_key_event_file_student.file_path is '附件文件路径'; alter table t_key_event_file_student add constraint FK_T_KEY_EV_REF16_T_KEY_EV foreign key (key_event_score_student_id) references t_key_event_score_student (id) on delete restrict on update res...
# RESTRICT 和 NO ACTION 具有相同的语义,两者本质不同在于 NO ACTION 允许关联检查推迟到事务的最后,而 RESTRICT 则会马上报错。 # SET NULL 主表在 on delete/update 时,设置从表外键为 NULL。 # SET DEFAULT 主表在 on delete/update 时,设置从表外键为 DEFAULT(默认值)。 CREATE TABLE products ( produ...
Restricting and cascading deletes are the two most common options.RESTRICTprevents deletion of a referenced row.NO ACTIONmeans that if any referencing rows still exist when the constraint is checked, an error is raised; this is the default behavior if you do not specify anything. (The essential...
DROPFUNCTION[IFEXISTS] 函数名 [([参数模式] [参数名] 参数类型)] [CASCADE|RESTRICT] DROPFUNCTION:删除一个函数 IFEXISTS: 如果函数不存在则不抛出错误而是报告消息 CASCADE :自动删除依赖于该函数的对象(如:触发器,操作符),然后删除所有依赖于该对象的对象 ...
order_id integer REFERENCES orders ON DELETE CASCADE, --级联删除选项 quantity integer, PRIMARY KEY (product_no, order_id) ); 1. 2. 3. 4. 5. 6. 限制和级联删除是两种最常见的选项。RESTRICT 禁止删除被引用的行。 NO ACTION 的意思是如果在检查约束的时候,如果还存在任何引用行,则抛出错误; 如果...
在正常情况下,我希望这些约束使用默认的ON DELETE RESTRICT行为。但在尝试与顾问共享数据库的快照时,我需要删除一些敏感数据。我希望我对DELETE FROM Table CASCADE命令的记忆不是纯粹的幻觉。我最后做的是转储数据库,编写一个脚本来处理转储,方法是添加ON DELETE CASCADE子句和所有外键约束,从中恢复,执行删除,再次转储...
{ { SELECT | INSERT | UPDATE | DELETE | RULE | REFERENCES | TRIGGER } [,...] | ALL [ PRIVILEGES ] } ON [ TABLE ] table_name [, ...] FROM { username | GROUP group_name | PUBLIC } [, ...] [ CASCADE | RESTRICT ]
REVOKE [ GRANT OPTION FOR ] { { SELECT | INSERT | UPDATE | DELETE | RULE | REFERENCES | TRIGGER } [,...] | ALL [ PRIVILEGES ] } ON [ TABLE ] table_name [, ...] FROM { username | GROUP group_name | PUBLIC } [, ...] [ CASCADE | RESTRICT ] REVOKE [ GRANT OPTION FOR ...
(id)on delete restrict on update restrict;';EXECUTE strSQL;---指定序列strSQL :='create sequence t_self_evaluation_'||currsnum||'_id_seq increment by 1minvalue 1 maxvalue 9223372036854775807 start with 1owned by t_self_evaluation_'||currsnum||'.id';EXECUTE strSQL;rownum := rownum +...