ALTERTABLEsuppliersSETUNUSEDCOLUMNfax;Code language:SQL (Structured Query Language)(sql) From now on, you cannot access thefaxcolumn anymore: SELECT*FROMsuppliers;Code language:SQL (Structured Query Language)(sql) You can view the number of unused columns per table from theDBA_UNUSED_COL_TABSview...
SQL> alter table test_compress compress for all operations; Table altered. SQL> alter table test_compress drop column object_name; Table altered. In 11g it is allowed to drop columns from a compressed table IF compatible is set to 11.1 or higher AND table was created with the "compress for...
sql ALTER TABLE employees DROP COLUMN middle_name; 验证列是否已成功从表中删除: 你可以通过查询表的结构来验证列是否已被成功删除。这可以通过DESC命令或查询ALL_TAB_COLUMNS视图来实现。 sql DESC employees; 或者: sql SELECT COLUMN_NAME FROM ALL_TAB_COLUMNS WHERE TABLE_NAME = 'EMPLOYEES' AND OWNER...
構文およびセマンティクスの詳細は、『Oracle Database PL/SQL言語リファレンス』を参照してください。CREATE TYPE文を使用すると、オブジェクト型、SQLJオブジェクト型、名前付きの可変配列(VARRAY)、ネストした表型または不完全なオブジェクト型の仕様部を作成できます。CREATE TYPE文およびCREATE...
SQL Server: ALTER TABLE Customer DROP COLUMN Birth_Date;Oracle: ALTER TABLE Customer DROP COLUMN Birth_Date;Google BigQuery: ALTER TABLE Customer DROP COLUMN Birth_Date;The resulting table structure is: Table Customer Column Name Data Type First_Name char(50) Last_Name char(50) ...
SQL> alter table test_compress compress for all operations; Table altered. SQL> alter table test_compress drop column object_name; Table altered. In 11g it is allowed to drop columns from a compressed table IF compatible is set to 11.1 or higher AND table was created with the "compress for...
我 们要删除表中不用的字段,如果直接drop column,对于大表,进行DDL操作的时间会比较长,会严重阻塞DML语句,导致应用服务器crash,通常的做法是先set unused column column_name 或者 set unused column_name,column_name...,然后再利用停机时间做alter table table_name drop unused columns。
SQL> ALTER TABLE t1 DROP UNUSED COLUMNS; ALTER TABLE t1 DROP UNUSED COLUMNS * ERROR at line 1: ORA-39726: unsupported add/drop column operation on compressed tables SQL> alter table t1 compress for oltp; Table altered. SQL> ALTER TABLE t1 DROP UNUSED COLUMNS; ...
只要有CPU,我想要完成的是启动一个新进程(查询+过滤器+ Parquet持久化)。def drop_constant_columns( 浏览1提问于2018-05-25得票数 0 回答已采纳 2回答 跟踪Oracle中的drop列进度 、、 我在Oracle中对一个巨大的表(1.8TB大小)发出了以下语句:它已经运行了近10天,由于内存不足而崩溃了几次。我继续写道:我...
In Oracle, the possibility to drop a column/columns in an existing table can be available only after the origin of oracle 8i. The column/columns in a table can be dropped either logically or physically, but most of the time we use the logic delete. And for this the "ALTER TABLE" ...