MySQL:截断表与从表中删除

Question

我们什么时候使用 DELETE 命令与 TRUNCATE 命令？我试图在 Internet 上查找，但两个命令都删除了数据；我无法区分。

Answer 1

从表中删除

1. DELETE is a DML Command.
2. DELETE statement is executed using a row lock, each row in the table is locked for deletion.
3. We can specify filters in where clause
4. It deletes specified data if where condition exists.
5. Delete activates a trigger because the operation are logged individually.
6. Slower than truncate because, it keeps logs.
7. Rollback is possible.
8. LIMIT clause can also be used to set a limit on the number of rows to be deleted.
9. ORDER BY clause can be used in DELETE statement. In this case, the rows are deleted in the specified order.

截断表

1. TRUNCATE is a DDL command.
2. TRUNCATE TABLE always locks the table and page but not each row.
3. Cannot use Where Condition.
4. It Removes all the data reset the auto increment number.
5. TRUNCATE TABLE cannot activate a trigger because the operation does not log individual row deletions.
6. Faster in performance wise, because it doesn't keep any logs.
7. Rollback is possible.
8. Cannot use LIMIT and ORDER BY.

DELETE 和 TRUNCATE 都可以在与 TRANSACTION 一起使用时回滚。 如果存在自增主键，truncate 会重置计数器。