In PostgreSQL, the constraints are used to apply some rules on the table’s column. In Postgres, theNOT NULLconstraint prevents NULL entries from being inserted into a column. In simple terms, the table columns declared with aNOT NULLconstraint take only non-null entries. In Postgres, theNOT...
However, to drop a table that is referenced by a view or a foreign-key constraint of another table,CASCADEmust be specified. (CASCADEwill remove a dependent view entirely, but in the foreign-key case it will only remove the foreign-key constraint, not the other table entirely.) Name DELETE...
-- 假设你有一个分区表,并且想要删除一个列 ALTER TABLE table_name DROP CONSTRAINT constraint_name; -- 删除依赖的约束 ALTER TABLE table_name DROP COLUMN column_name; -- 尝试删除列 请注意,上述代码可能需要根据你具体的Hive版本和表结构进行调整。 进一步诊断: 如果问题仍然存在,尝试简化你的SQL语句,逐...
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.) 1...
2) Drop a column that is referenced by a constraint First, attempt to remove the publisher_id column from the books table: ALTER TABLE books DROP COLUMN publisher_id; PostgreSQL issued the following error: ERROR: cannot drop table books column publisher_id because other objects depend on it ...
PostgreSQL 13.1 手册 一、 管理操作 1.数据库对象Size查询 2.恢释放磁盘空间 VACUUM regclass; --释放具体的表(不会给操作系统,不会减少磁盘使用量) VACUUM FULL regclass;–立即释放磁盘空间给操作系统(可能锁表) 3.数据库锁表 查找所有活动的被锁的表 ...
ALTER TABLE job_history DROP CONSTRAINT index_job_id; Output:Now see the structure of the table job_history after being altered.postgres=# \d job_history Column | Type | Modifiers ---+---+--- employee_id | numeric(6,0) | start_date | date | end_date | date | job_id | characte...
it is possible to encounter a duplicate key entry error (ERROR 1062 (23000): Duplicate entry), even if the duplicate entry is only temporary and would be reverted by a later entry in the online log. This is similar to the idea of a foreign key constraint check in InnoDB in which const...
Create schema in PostgreSQL 16.1 CREATE SCHEMA enters a new schema into the current database. The schema name must be distinct from the name of any existing schema in the current database. Syntax: CREATE SCHEMA schema_name [ AUTHORIZATION user_name ] [ schema_element [ ... ] ] ...
sql脚本如下所示: GO alter table TESTPersonsProject drop constraint FK_TESTPersonsProject_TESTprojectalter table TESTSideResearch drop constraint FK_TESTSideResearch_TESTproject 浏览0提问于2015-06-29得票数 0 5回答 Web SQL DROP/DELETE Table不工作 、 我尝试了几个不同的命令来清除我的Web SQL数据库,...