RE: Enum Type...

[Charles Zhao]

Forgot to mention, I am using InnoDB, but I am new to this.

-----Original Message-----
From: Mark Matthews [mailto:mark@stripped] 
Sent: Thursday, May 29, 2003 2:50 PM
To: Zhao, Charles
Cc: Nick Scholtz; harsh; java@stripped
Subject: Re: Enum Type...


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Zhao, Charles wrote:

> I had a similar question like this.  So if you insert an illegal value

> into a ENUM column, it will be automatically set to ""?  That's not 
> good for me.  I was hoping if it's illegal value then the db should 
> give me an error msg and reject the record.

The problem is, how do you make 'rejections' work with non-transactional
tables (like MyISAM, which is the default table type in MySQL)?

You have to remember that relational databases do operations as 'sets',
not on a record-by-record basis, so thinking in a record-by-record way
is sometimes going to lead you down the wrong path. MySQL can't reject a
record, because changes might have already been done to it can be
'rolled back', as parts of it might have already been updated.

See http://www.mysql.com/doc/en/constraint_NOT_NULL.html for the full
explanation (which is linked to from the documentation for 'ENUM' and
'SET' types as well).

	-Mark
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