如果删除B表中的记录,则会级联删除A表中对应记录 createtabletest(id serialprimarykey, namevarchar(10)); createtabletest01(id serialprimarykey, tidint,constraintfk_test01_tidforeignkey(tid)referencestest(id)ondeletecascade); imos=#insertintotest(name)values('a'),('b'),('c');INSERT03imos=#ins...
在PostgreSQL中,级联条件是指在删除操作中,同时删除与被删除记录相关联的其他记录。要删除PostgreSQL中的级联条件,可以使用外键约束和ON DELETE CASCADE选项。 外键约束是一种关系型数据库中的约束,用于确保两个表之间的数据一致性。在PostgreSQL中,可以通过在表的定义中使用FOREIGN KEY关键字来创建外键约束。例如,假设有...
on_delete=models.CASCADE) on_delete参数如下: CASCADE：级联操作。
如果删除B表中的记录,则会级联删除A表中对应记录 create table test(id serial primary key, name varchar(10)); 1. create table test01(id serial primary key, tid int, constraint fk_test01_tid foreign key(tid) references test(id) on delete cascade); 1. 2. imos=# insert into test(name) ...
dept_no int NOT NULL , FOREIGN KEY(dept_no) REFERENCES t_dept(dept_no) ON DELETE CASCADE -- 删除外键时,引用外键的记录设置为空 dept_no int , FOREIGN KEY(dept_no) REFERENCES t_dept(dept_no) ON DELETE SET NULL 1. 2. 3. 4. 5. 6. 7....
DETAIL:Key(a, b)=(1,1)isstill referencedfromtable"tbl_foreign". 测试例2.match full on delete cascade on update cascade 删除外键约束,清空数据,重新增加外键 test=#altertabletbl_foreigndropconstraintfk_tbl_foreign_a_b ;ALTERTABLEtest=#deletefromtbl_foreign;DELETE4test=#altertabletbl_foreignaddcon...
cust_id INTEGER PRIMARY KEY, cust_name TEXT NOT NULL ); Now create one more table named “order_details” with two regular columns and a foreign key: CREATE TABLE order_details( order_id INTEGER PRIMARY KEY, customer_id INTEGER REFERENCES customer_details (cust_id) ON DELETE CASCADE, ...
Third, delete a department and observe the cascading effect on associated employees: DELETE FROM departments WHERE id = 1; Once you execute this statement, it deletes all employees belonging to the department with department_id = 1 due to the DELETE CASCADE action defined on the foreign key co...
包含PRIMARY KEY、UNIQUE KEY、FOREIGN KEY、DATATYPE(内置数据类型)和DEFAULT CONSTRAINT。 VIEW、PROCEDURE(PostgreSQL的版本需为11及以上)、FUNCTION、RULE、SEQUENCE、EXTENSION、TRIGGER、AGGREGATE、INDEX、OPERATOR、DOMAIN 支持增量迁移的SQL操作 操作类型 SQL操作语句 ...
DELETE 删除一个表中的行。 DELETE FROM [ ONLY ] table [ WHERE condition ] DROP AGGREGATE 删除一个用户定义的聚集函数。 DROP AGGREGATE name ( type ) [ CASCADE | RESTRICT ] DROP CAST 删除一个用户定义的类型转换。 DROP CAST (source_type AS target_type) [ CASCADE | RESTRICT ] ...