Oracle introduced theTRUNCATE TABLEstatement that allows you to delete all rows from a big table. The following illustrates the syntax of the OracleTRUNCATE TABLEstatement: TRUNCATETABLEschema_name.table_name [CASCADE] [[PRESERVE|PURGE]MATERIALIZEDVIEWLOG]] [[DROP|REUSE]]STORAGE]Code language:SQL (...
Use theTRUNCATEstatement to remove all rows from a table or cluster. By default, Oracle Database also deallocates all space used by the removed rows except that specified by theMINEXTENTSstorage parameter and sets theNEXTstorage parameter to the size of the last extent removed from the segment ...
A table lock, also called a TM lock, is acquired by a transaction when a table is modified by an INSERT, UPDATE, DELETE, MERGE, SELECT with the FOR UPDATE clause, or LOCK TABLE statement. DML operations require table locks to reserve DML access to the table on behalf of a transaction ...
一、TRUNCATE TABLE 语法 TRUNCATE TABLE [schema_name.]table_name [ PRESERVE MATERIALIZED VIEW LOG | PURGE MATERIALIZED VIEW LOG ] [ DROP STORAGE | REUSE STORAGE ] ; --下面仅列出reuse storage的说明部分 REUSE STORAGE Specify REUSE STORAGE to retain the space from the deleted rows allocated to th...
TRUNCATE LOGOFF事件只可以指定触发时间为BEFORE。SUSPEND和LOGON事件只可以触发时间为AFTER。 创建一个用户事件的触发器,用来记录用户SCOTT所删除的所有对象。 以用户SCOTT身份连接到数据库,并创建一个用户存储信息的表: CREATE TABLE SCOTT.DROP_OBJ (object_name varchar2(20), object_type varchar2(20), dropped_...
TRUNCATE TABLE with REUSE STORAGE performs several orders of magnitude faster than deleting all rows, but has the following drawbacks: •You cannot roll back a TRUNCATE TABLE statement. •All cursors are invalidated. •You cannot flash back to the state of the table before the truncate opera...
?You cannot roll back a TRUNCATE TABLE statement. ?All cursors are invalidated. ?You cannot flash back to the state of the table before the truncate operation. This clause is not valid for temporary tables. A session becomes unbound from the temporary table when the table is truncated, so ...
1、在功能上,truncate是清空一个表的内容,它相当于delete from table_name。 2、delete是dml操作,truncate是ddl操作;因此,用delete删除整个表的数据时,会产生大量的roolback,占用很多的rollback segments, 而truncate不会。 3、在内存中,用delete删除数据,表空间中其被删除数据的表占用的空间还在,便于以后的使用,另...
在SQL下输入:truncate table 表名; 或者 在SQL下输入:delete * from 表名; TRUNCATE TABLE 在功能上与不带 WHERE 子句的 DELETE 语句相同:二者均删除表中的全部行。但 TRUNCATE TABLE 比 DELETE 速度快,且使用的系统和事务日志资源少。 DELETE 语句每次删除一行,并在事务日志中为所删除的每行记录一项。TRUNCATE...
The TRUNCATE statement has two basic formats: TRUNCATE TABLETRUNCATE TABLEREUSE STORAGE; Both statements delete all rows in a table. The rows are not physically deleted; instead the pointers are adjusted so that the table appears to be empty. ...