Selon Michael Kruckenberg <[EMAIL PROTECTED]>:
> A trigger is a good place to check the value, and change it, bit I
> don't believe you can actually generate a MySQL error within the
> trigger that will prevent the data from being inserted. Currently
> (unless there's been an update to triggers that's not yet in the
> docs), you can only change the value before it gets inserted.
>
> If you are looking to enforce the values going into your JobType
> column, you might be better off creating a JobType table, with a
> foreign key restraint between the tblJob.JobType and JobType.Name,
> and make sure that the only entries in the JobType.Name column are
> those you want to appear in the tblJob.JobType column.
>
> On Jun 25, 2005, at 10:28 AM, Chris Andrew wrote:
>
> > Dear List,
> >
> > My system is RedHat EL3 and MySQL 5.0.7-beta.
> >
> > I wanted to implement a check constraint (below), but after some
> > testing
> > and googling, it seems I can't do this with MySQL. I've read
> > suggestions
> > that check(s) should be done using triggers. Is a trigger a preferred
> > method of achieving the following:
> >
> > CREATE TABLE tblJob (
> > JobId SMALLINT UNSIGNED NOT NULL,
> > CustomerId SMALLINT UNSIGNED NOT NULL,
> > JobType VARCHAR(20) NOT NULL DEFAULT 'DesignInstall',
> > Description VARCHAR(100) NOT NULL,
> > QuotationDate DATE NOT NULL,
> > OrderDate DATE,
> > CHECK (JobType IN ('DesignOnly', 'DesignInstall', 'InstallOnly')),
> > PRIMARY KEY (JobId, CustomerId)
> > ) TYPE=InnoDB;
> >
> > Regards,
> > Chris
> >
> >
> >
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> >
>
> Mike Kruckenberg
> [EMAIL PROTECTED]
> "ProMySQL" Author
> http://www.amazon.com/exec/obidos/ASIN/159059505X
>
>
>
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>
Hi,
Use enum with a default type and let mysql do the check for you.
Hope that helps
:o)
Mathias
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