DELETE语句:该命令只根据where子句中给定的条件从表中删除行，如果没有指定条件，则从表中删除所有行。但是它不会释放包含表的空间。

SQL DELETE语句的语法是:

DELETE FROM table_name [WHERE condition];

TRUNCATE语句:该命令用于删除表中的所有行，并释放包含表的空间。

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。

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)              |
+----------------------------------------+----------------------------------------------+

它方便的一个重要原因是，当您需要刷新数百万行表中的数据，但又不想重新构建它时。“Delete *”会花费很长时间，而Truncate对性能的影响可以忽略不计。

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。

DELETE语句:该命令只根据where子句中给定的条件从表中删除行，如果没有指定条件，则从表中删除所有行。但是它不会释放包含表的空间。

SQL DELETE语句的语法是:

DELETE FROM table_name [WHERE condition];

TRUNCATE语句:该命令用于删除表中的所有行，并释放包含表的空间。