DELETE与TRUNCATE有什么不同
DELETE与TRUNCATE有什么不同 删除表中的数据的方法有delete,truncate, 它们都是删除表中的数据,而不能删除表结构,delete 可以删除整个表的数据也可以删除表中某一条或N条满足条件的数据,而truncate只能删除整个表的数据,一般我们把delete 操作叫作删除表,而t
DELETE与TRUNCATE有什么不同
删除表中的数据的方法有delete,truncate,
它们都是删除表中的数据,而不能删除表结构,delete 可以删除整个表的数据也可以删除表中某一条或N条满足条件的数据,而truncate只能删除整个表的数据,一般我们把delete 操作叫作删除表,而truncate操作叫作截断表.
truncate 操作与 delete 操作对比
操作
回滚
高水线
空间
效率
Truncate
不能
下降
回收
快
delete
可以
不变
不回收
慢
TRUNCATE和DELETE有以下几点区别
1、TRUNCATE在各种表上无论是大的还是小的都非常快。如果有ROLLBACK命令DELETE将被撤销，而TRUNCATE则不会被撤销。
2、TRUNCATE是一个DDL语言，向其他所有的DDL语言一样，他将被隐式提交，不能对TRUNCATE使用ROLLBACK命令。
3、TRUNCATE将重新设置高水平线和所有的索引。在对整个表和索引进行完全浏览时，经过TRUNCATE操作后的表比DELETE操作后的表要快得多。
4、TRUNCATE不能触发任何DELETE触发器。
5、不能授予任何人清空他人的表的权限。
6、当表被清空后表和表的索引将重新设置成初始大小，而delete则不能。
7、不能清空父表。
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