To do this, we type in the following: MySQL: ALTER TABLE Customer DROP INDEX Con_First;Note that MySQL uses DROP INDEX for index-type constraints such as UNIQUE. Oracle: ALTER TABLE Customer DROP CONSTRAINT Con_First;SQL Server: ...
SQL> drop table t; drop table t * ERROR at line 1: ORA-02449: unique/primary keys in table referenced by foreign keys (违反了constraint,员工销售表t1有參照到table t,这个reference relation不允许你drop table t) SQL> drop table t cascade constraints; Table dropped. SQL> select * from t1; ...
DROP a UNIQUE ConstraintTo drop a UNIQUE constraint, use the following SQL:SQL Server / Oracle / MS Access:ALTER TABLE Persons DROP CONSTRAINT UC_Person; MySQL:ALTER TABLE Persons DROP INDEX UC_Person; DROP a PRIMARY KEY ConstraintTo drop a PRIMARY KEY constraint, use the following SQL:...
In Oracle, SQL Server, and Google BigQuery, the syntax for ALTER TABLE Drop Column is, ALTER TABLE "table_name" DROP COLUMN "column_name"; Let's look at the example. Assuming our starting point is the Customer table created in the CREATE TABLE section: Table Customer ...
SQL> 我们可以发现利用Drop table cascade constraints可以以刪除关联table t的constraint來达成你drop table t的目的,原來属于t1的foreign key constraint已经跟随着被删除掉了,但是,储存在table t1的资料可不会被删除,也就是说Drop table cascade constraints 是不影响到存储于objec里的row data。
当删除事件监视器或用法列表时,该语句的授权标识所拥有的特权必须包括 SQLADM 或 DBADM 权限。 在删除用户映射时,如果此授权标识与该映射中的联合数据库授权名称不同,那么该语句的授权标识所拥有的特权必须包含 DBADM 权限。 否则,如果授权标识和授权名称匹配,那么不需要任何权限或特权。
To drop the parent table along with the referential integrity constraint, you can use the DROP TABLE command with CASCADE CONSTRAINTS in Oracle, as shown below. SQL Script: Cascade Constraints in Oracle Copy DROP TABLE Employee CASCADE CONSTRAINTS;DROP...
CONSTRAINT fk_brand FOREIGN KEY (brand_id) REFERENCES brands(brand_id) ON DELETE CASCADE ); 在这些表中,每个品牌有一个或更多的汽车,而每辆汽车只有一个品牌。 以下语句尝试删除brands表: DROP TABLE brands; Oracle发出以下错误: ORA-02449: unique/primary keys in table referenced by foreign keys ...
353 354 FOREIGN KEY、CHECK 和REFERENCES 子句实际上不做任何事情,除了对于 InnoDB 类型的表,它支持 ADD CONSTRAINT FOREIGN KEY (...) REFERENCES ... (...)。注意,InnoDB 不允许一个 index_name 被指定。查看章节 7.5 InnoDB 表。对于其它类型的表,这个句法仅仅为了兼容而提供,以更容易地从其它 SQL 服务...
CREATE CONSTRAINT ON () ASSERT <property_name> IS UNIQUE 用以下语法从节点或关系的的<property_name>中删除唯一约束: 代码语言:javascript 代码运行次数:0 运行 AI代码解释 DROP CONSTRAINT ON () ASSERT <property_name> IS UNIQUE 本文参与 腾讯云自媒体同步曝光计划,分享自作者个人站点/博客。 如有侵权请联系...