SQL中TRUNCATE和DELETE的区别是什么?

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当前回答

DELETE语句可以有一个WHERE子句来删除特定的记录,而TRUNCATE语句不需要任何子句并擦除整个表。 重要的是,DELETE语句记录删除日期,而TRUNCATE语句不记录删除日期。

其他回答

truncate和delete的区别如下:

+----------------------------------------+----------------------------------------------+
|                Truncate                |                    Delete                    |
+----------------------------------------+----------------------------------------------+
| We can't Rollback after performing     | We can Rollback after delete.                |
| Truncate.                              |                                              |
|                                        |                                              |
| Example:                               | Example:                                     |
| BEGIN TRAN                             | BEGIN TRAN                                   |
| TRUNCATE TABLE tranTest                | DELETE FROM tranTest                         |
| SELECT * FROM tranTest                 | SELECT * FROM tranTest                       |
| ROLLBACK                               | ROLLBACK                                     |
| SELECT * FROM tranTest                 | SELECT * FROM tranTest                       |
+----------------------------------------+----------------------------------------------+
| Truncate reset identity of table.      | Delete does not reset identity of table.     |
+----------------------------------------+----------------------------------------------+
| It locks the entire table.             | It locks the table row.                      |
+----------------------------------------+----------------------------------------------+
| Its DDL(Data Definition Language)      | Its DML(Data Manipulation Language)          |
| command.                               | command.                                     |
+----------------------------------------+----------------------------------------------+
| We can't use WHERE clause with it.     | We can use WHERE to filter data to delete.   |
+----------------------------------------+----------------------------------------------+
| Trigger is not fired while truncate.   | Trigger is fired.                            |
+----------------------------------------+----------------------------------------------+
| Syntax :                               | Syntax :                                     |
| 1) TRUNCATE TABLE table_name           | 1) DELETE FROM table_name                    |
|                                        | 2) DELETE FROM table_name WHERE              |
|                                        |    example_column_id IN (1,2,3)              |
+----------------------------------------+----------------------------------------------+

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。

详情请点击这里

如果将TRUNCATE包装在事务中,则可以回滚。

请参阅下面的两个参考资料并自行测试:-

http://blog.sqlauthority.com/2007/12/26/sql-server-truncate-cant-be-rolled-back-using-log-files-after-transaction-session-is-closed/

http://sqlblog.com/blogs/kalen_delaney/archive/2010/10/12/tsql-tuesday-11-rolling-back-truncate-table.aspx

截断与删除是SQL面试中最臭名昭著的问题之一。一定要向面试官解释清楚,否则可能会让你丢掉这份工作。问题是没有多少人意识到这一点,所以如果你告诉他们YES Truncate可以回滚,他们很可能会认为答案是错误的。

一眨眼的功夫就不能做DDL。

简而言之,truncate不会记录任何内容(因此更快,但不能撤消),而delete会记录日志(并且可以是更大事务的一部分,将回滚等)。如果您在开发中有不想在表中使用的数据,通常最好截断,因为您不会冒填满事务日志的风险