The manual is your friend! CHECK constraints are not supported in
mysql. "The CHECK clause is parsed but ignored by all storage engines."
<http://dev.mysql.com/doc/mysql/en/create-table.html>.
Using your example, you can easily verify this with SHOW CREATE TABLE:
mysql> SHOW CREATE TABLE employee;
+----------+-------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table
|
+----------+-------------------------------------------------------------------------------------------------------------------------------------------+
| employee | CREATE TABLE `employee` (
`name` varchar(30) default NULL,
`salary` decimal(10,2) default NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 |
+----------+-------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.05 sec)
As you can see, there is no check constraint.
Michael
mfatene@stripped wrote:
> Hi,
> The syntaxe is here, but the constraints seems not to be checked. Is this a bug
> ? i don't know !
>
> mysql> create table employee (
> -> name varchar(30),
> -> salary numeric(10,2),
> -> constraint check (salary > 0)
> -> );
> Query OK, 0 rows affected (0.22 sec)
>
> mysql>
> mysql>
> mysql> desc employee
> -> ;
> +--------+---------------+------+-----+---------+-------+
> | Field | Type | Null | Key | Default | Extra |
> +--------+---------------+------+-----+---------+-------+
> | name | varchar(30) | YES | | NULL | |
> | salary | decimal(10,2) | YES | | NULL | |
> +--------+---------------+------+-----+---------+-------+
> 2 rows in set (0.03 sec)
>
> mysql> insert into employee value('name 1',0),('name 2',1000)
> -> ;
> Query OK, 2 rows affected (0.05 sec)
> Records: 2 Duplicates: 0 Warnings: 0
>
> mysql> select * from employee;
> +--------+---------+
> | name | salary |
> +--------+---------+
> | name 1 | 0.00 |
> | name 2 | 1000.00 |
> +--------+---------+
> 2 rows in set (0.02 sec)
>
> Not null is checked :
> mysql> insert into employee value('name 1',null);
> ERROR 1048 (23000): Column 'salary' cannot be null
>
> But not a not '0' check constraint.
>
> Mathias
>
> Selon Rhino <rhino1@stripped>:
>
>
>>Are you sure this kind of constraint is supported in MySQL 4.1?
>>
>>I'm not saying they aren't, I just don't remember. Unless you're sure they
>>are, you should check the manual.
>>
>>Rhino
>>
>>----- Original Message -----
>>From: "Rodrigo Sakai" <rodrigo.sakai@stripped>
>>To: <mysql@stripped>
>>Sent: Friday, May 20, 2005 6:49 PM
>>Subject: constraints
>>
>>
>> Hi, I need to do a constraint that checks if the field 'salary' of one
>>table is not smaller than zero. Like:
>>
>> create table employee (
>>
>> name varchar(30),
>> salary numeric(10,2)
>>
>> constraint ck_salary check (salary > 0)
>> );
>>
>> What´s the sintaxe? I'am not finding the correct sintaxe to do this
>>constraint.
>>
>> I'm using MySQL 4.1
