alter index pk_detno rebuild storage(initial 1m next 512k); ALTER INDEX emp_ix REBUILD REVERSE; Oracle8i 的新功能可以对索引的无用空间进行合并,它由下面命令完成: ALTER INDEX . . . COALESCE; 例如: ALTER INDEX ename_idx COALESCE; §3.5.3 删除索引 当不需要时可以将索引删除以释放出硬盘空间。...
Because thememberstable has a primary key columnmember_id, Oracle creates a new index for this column. To view all indexes of a table, you query from theall_indexesview: SELECTindex_name, index_type, visibility,statusFROMall_indexesWHEREtable_name ='MEMBERS';Code language:SQL (Structured Quer...
Oracle automatically creates an index key when a primary key is defined on a table, which improves the performance of queries. Moreover, this column cannot store null values that ensure uniqueness and data integrity. Create an Oracle Table with a PRIMARY KEY To create a table named “Mannequins...
Oracle does not index table rows in which all key columns are null except in the case of bitmap indexes. Therefore, if you want an index on all rows of a table, then you must either specifyNOTNULLconstraints for the index key columns or create a bitmap index. Restrictions on Bitmap I...
SQL> alter table larry_test add primary key (terminal_id); Table altered. 这样的SQL语句没有问题,但是将会有两个问题比较“讨厌”: 主键名称不知,由系统生成。在DBA[USER]_INDEXES中INDEX_NAME显示的'SYS'开头的基本上就是由系统自动产生的。
在OceanBase 数据库 Oracle 模式下,如果删除表中的任一索引列,则所创建的索引失效。 语法 CREATE[UNIQUE]INDEXindex_name ONtable_name(key_part,...)[index_type][index_options]index_type:USINGBTREEindex_options:index_option[index_option...]index_option:GLOBAL|LOCAL|COMMENT'string'|...
USING INDEX (Create unique index uid_test_uid on test_uid(name) tablespace TABLESPACE2); ) 当然,也可以分部来处理. create table testone(name varchar2(10 char)) TABLESPACE1; ALTER TABLE TESTONE ADD CONSTRAINT PK_TESTONE1 PRIMARY KEY(NAME) USING INDEX TABLESPACE TABLESPACE2; ...
MySQL / SQL Server / Oracle / MS Access: ALTER TABLE PersonsADDCONSTRAINTpk_PersonIDPRIMARYKEY (Id_P,LastName) 注释:如果您使用 ALTER TABLE 语句添加主键,必须把主键列声明为不包含 NULL 值(在表首次创建时)。 撤销PRIMARY KEY 约束 如需撤销 PRIMARY KEY 约束,请使用下面的 SQL: ...
When you create a primary key or unique constraint, Oracle Database will automatically create a unique index for you (assuming there isn't an index already available). In most cases you'll add the constraint to the table and let the database build the index for you....
SQL> alter table larry_test add primary key (terminal_id); Table altered. 这样的SQL语句没有问题,但是将会有两个问题比较“讨厌”: 主键名称不知,由系统生成。在DBA[USER]_INDEXES中INDEX_NAME显示的'SYS'开头的基本上就是由系统自动产生的。