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
[EMAIL PROTECTED] 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 <[EMAIL PROTECTED]>:
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" <[EMAIL PROTECTED]>
To: <mysql@lists.mysql.com>
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
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