Le 28/03/2015 18:58, Lewis Balentine a écrit :
> I have over three decades of dealing with SQL and I can still not
> understand how this myth got propagated.
>
> There is NO valid SQL reason why a table should be required to have a
> unique primary key or any predefined key for that matter. One can always
> use the row number (record number) if such a key is required for one's
> application.
>

The row number does not exist in all database systems (more precisely, 
it is not accessible to the outside), so I can't rely on that feature to 
identify a row uniquely.

Maybe the row id is not standard SQL, if "standard SQL" has any meaning.

Consequently, I need a unique index, usually the primary key.

If you can tell me how to get the row id of a row in MySQL, PostgreSQL 
and SQLite (mabe it has changed since the last time I looked at it), I 
will reconsider my position. :-)

Regards,

-- 
Benoît Minisini

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