Re: auto_increment

[Ben Clewett]

Are you sure, I just get:

CREATE TABLE ...
ERROR 1075 (42000): Incorrect table definition; there can be only one 
auto column and it must be defined as a key

On version 5.0.41.  What version are you using?



Hiep Nguyen wrote:
hi list,

reading manual on mysql regarding auto_increment with multiple-column 
index:

CREATE TABLE animals (
    grp ENUM('fish','mammal','bird') NOT NULL,
    id MEDIUMINT NOT NULL AUTO_INCREMENT,
    name CHAR(30) NOT NULL,
    PRIMARY KEY (grp,id)
);

INSERT INTO animals (grp,name) VALUES
    ('mammal','dog'),('mammal','cat'),
    ('bird','penguin'),('fish','lax'),('mammal','whale'),
    ('bird','ostrich');

SELECT * FROM animals ORDER BY grp,id;

+--------+----+---------+
| grp    | id | name    |
+--------+----+---------+
| fish   |  1 | lax     |
| mammal |  1 | dog     |
| mammal |  2 | cat     |
| mammal |  3 | whale   |
| bird   |  1 | penguin |
| bird   |  2 | ostrich |
+--------+----+---------+

my question is what id would be if i:

UPDATE `animals` SET `grp`='mammal' WHERE `grp`='bird' AND `id`='2' AND 
`name`='ostrich' LIMIT 1;

i'm confused on auto_increment now.

thanks


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