Possible Duplicate:
How to force MySQL to take 0 as a valid auto-increment value
I know I can do an update on an existing row, but is it possible to INSERT a row with the id 0?
mysql> create table inc( id INT NOT NULL AUTO_INCREMENT PRIMARY KEY, sz TEXT);
Query OK, 0 rows affected (0.10 sec)
mysql> insert into inc(id, sz) select 25, "a";
Query OK, 1 row affected (0.02 sec)
Records: 1 Duplicates: 0 Warnings: 0
mysql> insert into inc(id, sz) select 25, "a";
ERROR 1062 (23000): Duplicate entry '25' for key 'PRIMARY'
mysql> insert into inc(id, sz) select 27, "b";
Query OK, 1 row affected (0.04 sec)
Records: 1 Duplicates: 0 Warnings: 0
mysql> insert into inc(id, sz) select -5, "c";
Query OK, 1 row affected (0.03 sec)
Records: 1 Duplicates: 0 Warnings: 0
mysql> insert into inc(id, sz) select 0, "d";
Query OK, 1 row affected (0.15 sec)
Records: 1 Duplicates: 0 Warnings: 0
mysql> select * from inc;
+----+------+
| id | sz |
+----+------+
| -5 | c |
| 25 | a |
| 27 | b |
| 28 | d |
+----+------+
4 rows in set (0.00 sec)
From http://dev.mysql.com/doc/refman/5.0/en/example-auto-increment.html
"No value was specified for the AUTO_INCREMENT column, so MySQL assigned sequence numbers automatically. You can also explicitly assign NULL or 0 to the column to generate sequence numbers."
So it seems using 0 just tells it to auto_increment.
But if you are assigning ID numbers, I'm not sure why you have defined the column to use AUTO_INCREMENT?
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With