在MySQL 5.0中，是否可以在不更新auto_increment值的情况下插入带有auto_increment列的表中？

Question

I have a MySQL database, containing a table with an auto_increment primary key.

Consider the following definition as sufficient for this example:

create table test(id integer not null auto_increment primary key) engine=innodb;

Now, typically I would insert into this table using the following syntax:

insert into test() values();

This would appropriately update the auto_increment value, and that is fine.

However, I would like to insert a high value into this table (say, 1000000) but not have it update the auto_increment ID.

Is it possible to insert high values into this table in such a way as to not have an effect on the value of the auto_increment ID?

I know this is a terrible practice, but it would significantly simplify some things I have to do.

Thanks in advance.

Answer 1

MySQL 5.0 lets you insert an arbitrary value into an auto increment field, but this does alter the next value used for auto incrementing. And although you can alter the "next number" an auto increment field will use (with ALTER TABLE t AUTO_INCREMENT = number ), this has to be greater than the maximum value currently in that column.

So, no, it doesn't appear you can achieve what you asked.

Answer 2

You can just give your row the id you like. For example, given the following table definition:

CREATE TABLE IF NOT EXISTS `stack-test` (
  `id` int(10) unsigned NOT NULL auto_increment,
  `name` varchar(255),
  PRIMARY KEY  (`id`)
);

The following query will insert a row with a automatically generated id:

INSERT INTO `stack-test` (name) VALUES ('Peter');

And this query will insert a row with a user-defined id:

INSERT INTO `stack-test` (id, name) VALUES (5, 'Joe');

Verify by querying all rows:

SELECT * FROM `stack-test`;

Output:

+----+-------+
| id | name  |
+----+-------+
|  1 | peter |
|  5 | Joe   |
+----+-------+

Update: Just read, that you don't want to influence the AUTO_INCREMENT value. As staticsan mentioned, the AUTO_INCREMENT field automatically uses the highest value plus one. There is a statement which resets the counter to a certain value, but this only works, if there is no higher value present in the table:

ALTER TABLE `stack-test` AUTO_INCREMENT = 2;

Answer 3

I had a similar issue and though I like the answer above I resolved it by using two tables. One for high id's and the other for low ones. It suited my particular situation quite well fwiw.

Answer 4

How about reserving some initial values instead of final ones ? I mean, keep ids, say less than 1000 as reserved. Make auto increment seed as 1001 so that new inserts will have value after that and use IDENTITY INSERT to add values in reserved range.

Hope it helps.

Answer 5

我不这么认为-自动递增字段必须是主键，因此不为null。

Answer 6

This is not possible. To have things behave the way you're suggesting would introduce a duplicate auto_increment value when the counter eventually does get up to that very high number you've inserted.

Answer 7

sorry for stating the bleedin' obvious, and I'm not an RDBMS specialist at all, but isn't your requirement so "unorthodox" that it dictates another approach? You yourself say you know this is "terrible practice". Isn't the thing about auto-increment fields that they serve one purpose and one purpose only: to assign a unique ID to a particular record, and isn't it, um, absolutely wrong to attribute any significance whatever to the actual value?

So, ever so tentatively, might I suggest using another field to do what you want?