CREATE TABLE orders ( order_id integer PRIMARY KEY, product_no integer REFERENCES products, quantity integer ); # 定义多个 Column 组成的外键,要求被约束列(外键)的数量和类型应该匹配被引用列(主键)的数量和类型。 CREATE TABLE t1 ( a integer
1. However, to drop a table that is referenced by a view or a foreign-key constraint of another table, CASCADE must be specified. 1. (CASCADE will remove a dependent view entirely, but in the foreign-key case it will only remove the foreign-key constraint, not the other table entirely....
The PostgreSQL FOREIGN KEY is a combination of columns with values based on the primary key values from another table. A foreign key constraint, also known as Referential integrity Constraint, specifies that the values of the foreign key correspond to actual values of the primary key in the othe...
constraint_type有四种:UNIQUE、PRIMARY KEY、CHECK、FOREIGN KEY 通过修改上边sql语句的table_name和constraint_type来进行相应的查询 警告
ERROR: cannot truncate a table referenced in a foreign key constraint by a local table 截断本地协调器(coordinator)节点表数据对于分布式表是安全的,因为它们的行(如果有)将在分发过程中复制到 worker 节点。 undistribute_table undistribute_table() 函数撤消 create_distributed_table 或 create_reference_ta...
禁用t2表外键约束检查 FOREIGN_KEY_CHECKS=0 然后drop t1 原表 再rename _t1_new t1 这种方式速度更快,也不会阻塞请求。但有风险,第一,drop表的瞬间到rename过程,原表t1是不存在的,遇到请求会报错;第二,如果因为bug或某种原因,旧表已删,新表rename失败,那就太晚了,但这种情况很少见。
1. Missing CASCADE Clause:Attempting to delete a parent row without the CASCADE clause in the foreign key will result in an error: ERROR: update or delete on table "authors" violates foreign key constraint 2. Unintended Deletions:Cascading deletions can lead to loss of important data if not ...
ERROR: cannot truncate a table referenced in a foreign key constraint by a local table 截断本地协调器(coordinator)节点表数据对于分布式表是安全的,因为它们的行(如果有)将在分发过程中复制到 worker 节点。 undistribute_table undistribute_table() 函数撤消 create_distributed_table 或 create_reference_tabl...
In this post, I am sharing one option to Disable / Enable the Foreign Key Constraint in PostgreSQL. During data migration and testing purpose, Database Developer requires to disable Foreign key constraint of a Table. Once you disable constraint, then later you might need to...
[,...])postgres=#altertablespacetest_tbsrenametoprod_tbs;postgres=#altertablespacetest_tbsownertotest;--删除表空间postgres=#\helpdroptablespaceCommand:DROPTABLESPACEDescription:removeatablespaceSyntax:DROPTABLESPACE[IFEXISTS]namepostgres=#droptablespaceprod_tbs;DROPTABLESPACE--删除完后,自动生成的目录也会被...