SQL中TRUNCATE和DELETE的区别是什么?
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SQL中TRUNCATE和DELETE的区别是什么?
如果你的答案是针对特定平台的,请注明。
当前回答
最大的区别是truncate是不记录日志的操作,而delete是。
简单地说,这意味着在数据库崩溃的情况下,不能通过截断恢复所操作的数据,但可以通过删除恢复。
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其他回答
删除
DELETE是一个DML命令 DELETE可以回退 Delete =仅删除-因此可以回滚 在DELETE中,可以使用WHERE子句编写条件 语法- Delete from [Table] where [Condition]
截断
TRUNCATE是一个DDL命令 不能在TRUNCATE中回滚,TRUNCATE将永久删除该记录 Truncate = Delete+Commit -这样我们就不能回滚 不能在TRUNCATE中使用条件(WHERE子句) 语法- Truncate table [table]
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http://www.zilckh.com/what-is-the-difference-between-truncate-and-delete/
一眨眼的功夫就不能做DDL。
Truncate and Delete in SQL are two commands which is used to remove or delete data from table. Though quite basic in nature both Sql commands can create lot of trouble until you are familiar with details before using it. An Incorrect choice of command can result is either very slow process or can even blew up log segment, if too much data needs to be removed and log segment is not enough. That's why it's critical to know when to use truncate and delete command in SQL but before using these you should be aware of the Differences between Truncate and Delete, and based upon them, we should be able to find out when DELETE is better option for removing data or TRUNCATE should be used to purge tables.
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这两个操作的另一个区别是,如果表包含一个标识列,则在TRUNCATE下该列的计数器将重置1(或为该列定义的种子值)。DELETE没有这种影响。
在这个例子中,Truncate也可以被rollback
begin Tran
delete from Employee
select * from Employee
Rollback
select * from Employee