In a Real Application Clusters environment, this setting causes Oracle to perform a checkpoint only for the thread of redo log file groups for the instance from which you issue the statement. CHECK DATAFILES Clause In a distributed database system, such as a Real Application Clusters environme...
To enable a UNIQUE or PRIMARY KEY constraint, you must have the privileges necessary to create an index on the table. You need these privileges because Oracle creates an index on the columns of the unique or primary key in the schema containing the table. To enable or disable triggers, ...
[ INITIALLY DEFERRED | INITIALLY IMMEDIATE ] 而table_constraint是: [ CONSTRAINT constraint_name ] { CHECK ( expression ) [ NO INHERIT ] | UNIQUE ( column_name [, ... ] ) index_parameters | PRIMARY KEY ( column_name [, ... ] ) index_parameters | EXCLUDE [ USING index_method ] ( ...
唯一:ALTER TABLE tablename ADD CONSTRAINT constraint_name UNIQUE(colnamme)。 检查:ALTER TABLE tablename ADD CONSTRAINT constraint_name CHECK 后面跟着: 1.(colname IN (check_list)):限定列的取值为列表中的一个,如sex in ('F','M')。 2.(colname1 DETERMINED BY colname2):colname1完全依赖于col...
Adding or dropping one or more unique, referential, or check constraints Altering one or more referential or check constraint attributes Altering the caching of data at a federated server Invocation This statement can be embedded in an application program or issued through the use of dynamic SQL st...
常见的约束类型包括主键约束(PRIMARY KEY)、唯一约束(UNIQUE)、外键约束(FOREIGN KEY)、检查约束(CHECK)和非空约束(NOT NULL)。 3. 如何在ALTER TABLE语句中添加约束 在ALTER TABLE语句中,可以使用ADD CONSTRAINT子句来添加约束。以下是添加不同类型约束的示例:...
getdate 这个函数orcale 里面没有，这个是SQL SERVER 用的，ORACLE表示当前时间 直接用：sysdate
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...
..) reference_definition | ADD [CONSTRAINT [symbol]] CHECK (expr) [[NOT] ENFORCED] | DROP {CHECK | CONSTRAINT} symbol | ALTER {CHECK | CONSTRAINT} symbol [NOT] ENFORCED | ALGORITHM [=] {DEFAULT | INSTANT | INPLACE | COPY} | ALTER [COLUMN] col_name { SET DEFAULT {literal | (...
Oracle Database - Enterprise Edition - Version 10.1.0.2 and laterInformation in this document applies to any platform.Symptoms After import of a table that contains a primary key constraint and corresponding index, a drop constraint does not drop the corresponding PK index. When trying to insert...