关于phpmyadmin：无法截断MySQL表，同时能够删除所有记录


Can't truncate MySQL table, while being able to delete all the records

我是一个非常初衷的关系，所以这可能听起来很愚蠢。 但是，在截断表和删除所有记录之间(在MySQL中)有什么区别(这个答案仅说明性能)？

我正在玩(在phpMyAdmin中)我的一个测试表，要检查，如何重置auto_increment表的值并进入情境，我能够删除所有记录：

1
DELETE from managers;

但是当我试图截断这个表(TRUNCATE managers)时，我发出了警告：Cannot truncate a table referenced in a foreign key constraint (probes, CONSTRAINT probes_ibfk_4 FOREIGN KEY (manager_id) REFERENCES managers (id));。

我必须用ALTER TABLE managers AUTO_INCREMENT = 1;"重置"auto_increment值。

这不奇怪吗？ 到目前为止，我认为，TRUNCATE = DELETE from managers(就检查和效果而言，因为性能可能不同，但这不是关键)。

如何在TRUNCATE上弹出约束警告而不是"全部删除"？

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truncate删除所有行后重置auto_increment。 所以它与使用DELETE命令删除所有行不同。

来自mysql参考：

TRUNCATE TABLE empties a table completely. Logically, this is
equivalent to a DELETE statement that deletes all rows, but there are
practical differences under some circumstances.

For an InnoDB table before version 5.0.3, InnoDB processes TRUNCATE
TABLE by deleting rows one by one. As of MySQL 5.0.3, row by row
deletion is used only if there are any FOREIGN KEY constraints that
reference the table. If there are no FOREIGN KEY constraints, InnoDB
performs fast truncation by dropping the original table and creating
an empty one with the same definition, which is much faster than
deleting rows one by one. (When fast truncation is used, it resets any
AUTO_INCREMENT counter to zero. From MySQL 5.0.13 on, the
AUTO_INCREMENT counter is reset to zero by TRUNCATE TABLE, regardless
of whether there is a foreign key constraint.)

In the case that FOREIGN KEY constraints reference the table, InnoDB
deletes rows one by one and processes the constraints on each one. If
the FOREIGN KEY constraint specifies DELETE CASCADE, rows from the
child (referenced) table are deleted, and the truncated table becomes
empty. If the FOREIGN KEY constraint does not specify CASCADE, the
TRUNCATE TABLE statement deletes rows one by one and stops if it
encounters a parent row that is referenced by the child, returning
this error:

ERROR 1451 (23000): Cannot delete or update a parent row: a foreign
key constraint fails (test.child, CONSTRAINT child_ibfk_1
FOREIGN KEY (parent_id) REFERENCES parent (id))

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