当我将列的大小从 BIGINT(11) 更改为 BIGINT(20) 时，MySql 表列删除了其 AI 标志

Question

我有一个表名称file_upload它的 upload_id 列为 BIGINT(11) AI PK NOT NULL当我将表列大小更改为 BIGINT(20) 时，AI 标志被删除，每次更改列中的任何内容时，是否都应该向列提供新的定义？

Answer 1

只有一个小注释。 BIGINT(10) 和 BIGINT(20) 之间没有真正的区别。您可以始终存储相同的值。仅与ZEROFILL一起使用时的尺寸。

查看我的示例

mysql> CREATE TABLE `bigints` (
    ->   `id` INT(11) UNSIGNED NOT NULL AUTO_INCREMENT,
    ->   `bigint1` BIGINT(1) UNSIGNED DEFAULT NULL,
    ->   `bigint10` BIGINT(10) UNSIGNED ZEROFILL DEFAULT NULL,
    ->   `bigint20` BIGINT(20) UNSIGNED ZEROFILL DEFAULT NULL,
    ->   PRIMARY KEY (`id`)
    -> ) ENGINE=INNODB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8;
Query OK, 0 rows affected (0,04 sec)

mysql>
mysql> INSERT INTO `bigints` (`id`, `bigint1`, `bigint10`, `bigint20`)
    -> VALUES
    ->     (1, 1, 1, 1),
    ->     (2, 100, 100, 100),
    ->     (3, 1000000000, 1000000000, 1000000000),
    ->     (4, 18446744073709551615, 18446744073709551615, 18446744073709551615);
Query OK, 4 rows affected (0,01 sec)
Records: 4  Duplicates: 0  Warnings: 0

mysql> SELECT * from bigints;
+----+----------------------+----------------------+----------------------+
| id | bigint1              | bigint10             | bigint20             |
+----+----------------------+----------------------+----------------------+
|  1 |                    1 |           0000000001 | 00000000000000000001 |
|  2 |                  100 |           0000000100 | 00000000000000000100 |
|  3 |           1000000000 |           1000000000 | 00000000001000000000 |
|  4 | 18446744073709551615 | 18446744073709551615 | 18446744073709551615 |
+----+----------------------+----------------------+----------------------+
4 rows in set (0,01 sec)

mysql>