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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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__ ___ ___ ____ __
/ |/ /_ __/ __/ __ \/ / Mark Matthews <mark@stripped>
/ /|_/ / // /\ \/ /_/ / /__ MySQL AB, SW Dev. Manager - J2EE/Windows
/_/ /_/\_, /___/\___\_\___/ Flossmoor (Chicago), IL USA
<___/ www.mysql.com
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