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。
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
通过发出TRUNCATE TABLE语句,您将指示SQL Server删除表中的每条记录,而不进行任何日志记录或事务处理。
其他回答
“Truncate不会记录任何东西”是正确的。我想更进一步:
Truncate不会在事务的上下文中执行。
截断比删除的速度优势应该是明显的。根据你的情况,这种优势从微不足道到巨大不等。
然而,我看到截断无意中破坏了引用完整性,并违反了其他约束。通过在事务外部修改数据而获得的权力,必须与在没有安全网的情况下走钢丝时继承的责任相平衡。
是的,DELETE比较慢,TRUNCATE比较快。为什么?
DELETE必须读取记录,检查约束,更新块,更新索引,并生成重做/撤销。所有这些都需要时间。
TRUNCATE只是在数据库中为表(High Water Mark)调整一个指针,然后!数据不见了。
这是Oracle特有的,AFAIK。
在SQL Server 2005中,我相信你可以回滚截断
DROP The DROP command removes a table from the database. All the tables' rows, indexes and privileges will also be removed. No DML triggers will be fired. The operation cannot be rolled back. TRUNCATE TRUNCATE removes all rows from a table. The operation cannot be rolled back and no triggers will be fired. As such, TRUNCATE is faster and doesn't use as much undo space as a DELETE. Table level lock will be added when Truncating. DELETE The DELETE command is used to remove rows from a table. A WHERE clause can be used to only remove some rows. If no WHERE condition is specified, all rows will be removed. After performing a DELETE operation you need to COMMIT or ROLLBACK the transaction to make the change permanent or to undo it. Note that this operation will cause all DELETE triggers on the table to fire. Row level lock will be added when deleting.
来自:http://www.orafaq.com/faq/difference_between_truncate_delete_and_drop_commands
SQL server中删除与截断的总结 完整文章请点击这个链接:http://codaffection.com/sql-server-article/delete-vs-truncate-in-sql-server/
摘自dotnet mob文章:删除Vs截断SQL Server