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: ...
To drop a DEFAULT constraint, use the following SQL: SQL Server / Oracle / MS Access: ALTERTABLEPersons ALTERCOLUMNCityDROPDEFAULT; MySQL: ALTERTABLEPersons ALTERCityDROPDEFAULT; DROP INDEX TheDROP INDEXcommand is used to delete an index in a table. ...
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; ...
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; ...
To remove a constraint, use theDROP CONSTRAINTclause in theALTER TABLEstatement. If you wish to drop the unique constraint on the “Email” column: ALTER TABLE Customers DROP CONSTRAINT UQ_Email; 4. Renaming Tables TheALTERcommand allows you to rename a table easily. Suppose you want to ren...
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 ...
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...
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...
技术标签:Oracle数据库SQLdropDDL 1 drop table时,相关约束被删除 如图,经过drop table操作后已找不到相关的constraint 2 drop table时,对相关对象的影响 如图,index是在tb1上建立的,view和synonym也是基于tb1建立的 (注意这里因为tb1是从recylebin里flashback回来的,因此i... ...
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...