mysql - mysql表id中的默认值

Question

我有主要的 id。它具有自动增量。

每当我尝试输入默认值时，例如：000 - 它不是从该数字开始计数，而是从 0、1、2、3 等开始计数......

我怎样才能使它成为000？

或者在我的情况下，我真的想要它作为发票 - 比如说 2011-000 并开始计算这可能吗？

有任何想法吗？？

Answer 1

为了使您的列包含 000，您需要将其设为zerofill. zerofill因此，使用您的列选项更改您的表格。

您可以阅读有关 zerofill 的更多信息，

http://dev.mysql.com/doc/refman/5.0/en/numeric-type-overview.html

此外，正如 ajreal 建议的那样，您需要将列物理更新为零。

Answer 2

Why you need to bother between 0000 and 0001 ?

PS - http://dev.mysql.com/doc/refman/5.0/en/server-sql-mode.html#sqlmode_no_auto_value_on_zero

NO_AUTO_VALUE_ON_ZERO affects handling of AUTO_INCREMENT columns. Normally, you generate the next sequence number for the column by inserting either NULL or 0 into it. NO_AUTO_VALUE_ON_ZERO suppresses this behavior for 0 so that only NULL generates the next sequence number.

This mode can be useful if 0 has been stored in a table's AUTO_INCREMENT column. (Storing 0 is not a recommended practice, by the way.) For example, if you dump the table with mysqldump and then reload it, MySQL normally generates new sequence numbers when it encounters the 0 values, resulting in a table with contents different from the one that was dumped. Enabling NO_AUTO_VALUE_ON_ZERO before reloading the dump file solves this problem. mysqldump now automatically includes in its output a statement that enables NO_AUTO_VALUE_ON_ZERO, to avoid this problem.

Hope the following make sense without change NO_AUTO_VALUE_ON_ZERO ...

mysql> create table invoice (years int(4) unsigned, 
seq int(4) unsigned zerofill not null auto_increment, 
primary key(years, seq));
Query OK, 0 rows affected (0.01 sec)

mysql> insert into invoice values (2011, 0);
Query OK, 1 row affected (0.00 sec)

mysql> update invoice set seq=0;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> alter table invoice auto_increment=0;
Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> insert into invoice values (2011, 0);
Query OK, 1 row affected (0.00 sec)

mysql> select * from invoice;
+-------+------+
| years | seq  |
+-------+------+
|  2011 | 0000 |
|  2011 | 0001 |
+-------+------+
2 rows in set (0.00 sec)

mysql> insert into invoice values (2011, 0), (2011, 0);
Query OK, 2 rows affected (0.00 sec)
Records: 2  Duplicates: 0  Warnings: 0

mysql> select * from invoice;
+-------+------+
| years | seq  |
+-------+------+
|  2011 | 0000 |
|  2011 | 0001 |
|  2011 | 0002 |
|  2011 | 0003 |
+-------+------+
4 rows in set (0.00 sec)

Answer 3

ALTER TABLE tablename AUTO_INCREMENT = 1