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:...
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。
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; ...
1、关于 cascade constraints 假设A为主表(既含有某一主键的表),B为从表(即引用了A的主键作为外键)。 则当删除A表时,如不特殊说明,则 drop table A 系统会出现错误警告的讯息而不会允许执行。 此时必须用,drop table A cascade constraints; SQL> select CONSTRAINT_NAME,TABLE_NAME from dba_constraints wher...
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...
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 constraints....
DROP [TEMPORARY] TABLE [ IF EXISTS ] [ schema_name. ]table_name [CASCADE CONSTRAINTS][ PURGE ] 参数说明 TEMPORARY 删除临时表,后面的表名只能是临时表。 IF EXISTS 表不存在时,返回成功。 [schema_name.]table_name 待删除表名。 CASCADE CONSTRAINTS ...
When a table is dropped, rules or defaults on it lose their binding, and any constraints associated with it are automatically dropped. If you re-create a table, you must rebind the appropriate rules and defaults, and add all necessary constraints. ...
In 2.15.3.0-b56, drop constraint with if exists gives a NOTICE if constraint does not exists. yugabyte=# ALTER TABLE contacts drop CONSTRAINT IF EXISTS D_FKEY_W; NOTICE: constraint "d_fkey_w" of relation "contacts" does not exist, skipping ALTER TABLE In 2.15.3.0-b107, drop constraint...