DROP TABLE Employee; Oracle 中具有级联约束的 DROP 表 如果Employee表有一些主键,在其他子表中引用,那么首先我们必须从子表中删除引用约束,然后才能删除父表。 要删除父表以及引用完整性约束,可以在 Oracle 中使用命令DROP TABLEwithCASCADE CONSTRAINTS,如下所示。 SQL 脚本:Oracle 中的级联约束 复制 DROP TABLE Em...
在Oracle数据库中, drop table语法如下: 即drop table时通过cascadeconstraints级联删除所有该表中的约束。 在LightDB 23.3版本中,drop table同样支持了constraints关键字,自动删除依赖于表的所有约束对象。语法结构如下: DROP TABLE [ IF EXISTS ] name [, ...] [ CASCADE[CONSTRAINTS ]| RESTRICT ] 具体使用如下:...
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; ...
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。
When a table is dropped, rules or defaults on the table lose their binding, and any constraints or triggers associated with the table are automatically dropped. If you re-create a table, you must rebind the appropriate rules and defaults, re-create any triggers, and add all required constra...
IfITableDefinitionWithConstraints::DropConstraintreturns any errors, the constraint is not dropped. If the session is participating in a transaction, if DBPROP_SUPPORTEDTXNDDL is DBPROPVAL_TC_DDL_IGNORE, and if the method succeeds, the operation is complete and is unaffected by subsequent calls to...
SQL Drop Table Examples with T-SQL and SQL Server Management Studio Disable, enable, drop and recreate SQL Server Foreign Keys Best practices for SQL Server database ALTER table operations Script all Primary Keys, Unique Constraints and Foreign Keys in a SQL Server database using T-SQL ...
使用ADD 语句向已有表中增加 columns, constraints,watermark。 向表新增列时可通过 FIRST or AFTER col_name 指定位置,不指定位置时默认追加在最后。 ADD 语句示例如下。 -- add a new column ALTER TABLE MyTable ADD category_id STRING COMMENT 'identifier of the category'; -- add columns, constraint, ...
The following example deletes a clustered index with aPRIMARY KEYconstraint by dropping the constraint. TheProductCostHistorytable has noFOREIGN KEYconstraints. If it did, those constraints would have to be removed first. SQL -- Set ONLINE = OFF to execute this example on editions other than En...
次の文は、sales_by_month_by_stateマテリアライズド・ビューおよびそのマテリアライズド・ビューの基礎となる表を削除します(基礎となる表がON PREBUILT TABLE句が指定されたCREATE MATERIALIZED VIEW文に登録されていない場合)。DROP MATERIALIZED VIEW sales_by_month_by_state; ...