What's the whole point of writing CHECK constraints in MySQL?

The MySQL Reference Manual says:

The CHECK clause is parsed but ignored by all storage engines.

No mistake. I've read that over 10 times.

So what's the whole point of writing check constr开发者_运维知识库aints then?

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It's there because of interoperability concerns. You can for example import an SQL script that is generated by other RDBMSs that support CHECK constraint (say Oracle).

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There is no point. I think they prepared the database to accept check constraints by adding support for them in the SQL parser but none of the engines still support them.

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It's been a bug report for over 7 years.

http://bugs.mysql.com/bug.php?id=3464

Personal opinion: another reason not to use MySQL, like NATURAL JOIN (and again) and random aggregates