Privileges on specific fields in a DB

[binary-nomad]

How do I make a table with fields again, say, name, age, address, wife
etc. that I want people to be able to look at (with any client like
MysqlCC etc), but only be able to modify certain fields, eg. wife (this
includes deleting the field from the database, maybe) - the name, age
etc. must be left intact, ie. not changeable by anyone.
Thanks.

[Gordon Burditt]

>How do I make a table with fields again, say, name, age, address, wife

etc. that I want people to be able to look at (with any client like
MysqlCC etc), but only be able to modify certain fields, eg. wife (this
includes deleting the field from the database, maybe) - the name, age
etc. must be left intact, ie. not changeable by anyone.

You think 'age' is a field that is never going to change? It would be
best to store 'birth date', which really won't change.

You can't have a database not changeable by *anyone*. Even a CD-ROM
can be thrown into a fire, and hard disks can be re-formatted. The
admin of a system is going to have broad powers to replace MySQL
with a version that doesn't honor permissions.

Using MySQL permissions, you can create a login with privileges to
only modify certain fields. Look in the MySQL manual under
'GRANT and REVOKE syntax'.

If you are thinking of a web page, perhaps the application is better
written with the web page code (PHP?) written so it will not attempt
to change any fields but the ones you want changeable.

Gordon L. Burditt

[Markus Popp]

The solution is something like this:

grant select (name, age, address, wife), update (wife), delete (wife),
insert (wife) on database.table to 'user'@'host';

Markus

[Gordon Burditt]

>grant select (name, age, address, wife), update (wife), delete (wife),

insert (wife) on database.table to 'user'@'host';

Markus

What does it *MEAN* to have delete privileges on a column? You
delete a whole row, which affects all columns in that row. The
column-based privileges are select, update, insert, and references.

Gordon L. Burditt

[Phil Nospam]

"Gordon Burditt" <go****@hammy.burditt.org> wrote in message
news:11*************@corp.supernews.com...

grant select (name, age, address, wife), update (wife), delete (wife),
insert (wife) on database.table to 'user'@'host';

Markus

What does it *MEAN* to have delete privileges on a column? You
delete a whole row, which affects all columns in that row. The
column-based privileges are select, update, insert, and references.

Gordon L. Burditt

Sounds like he wants to give someone the ability to change a specific
record. For example, to allow me to select and examine my personal record,
add a wife if I get married, or delete a wife if I get divorced. If this is
correct, then having update privledges on the wife field would allow someone
to do that.

Is this correct, Markus?

Phil

[Gordon Burditt]

>> >grant select (name, age, address, wife), update (wife), delete (wife),

>insert (wife) on database.table to 'user'@'host';
>
>Markus
What does it *MEAN* to have delete privileges on a column? You
delete a whole row, which affects all columns in that row. The
column-based privileges are select, update, insert, and references.

Gordon L. Burditt

Sounds like he wants to give someone the ability to change a specific
record.

MySQL grant privileges alone do not offer that ability. You
can do it with views and grant privileges on the view, not the
underlying table. You might also do it with triggers.
For example, to allow me to select and examine my personal record,
add a wife if I get married, or delete a wife if I get divorced. If this is
correct, then having update privledges on the wife field would allow someone
to do that.

That's not what the 'delete' privilege means. You don't delete a
column in a specific row; you set it to null. You'd need update,
not delete, privilege to change the field from one value to another.
'update' privilege on a column means that you can change the value
of that column in *EVERY* row. 'delete' (on a table-wide basis)
means the ability to delete rows.

Selective column privileges are more suited to the ability to
restrict a low-level HR employee to view ALL salaries but not change
ANY of them, and to not allow viewing or changing of passwords at
all.

Gordon L. Burditt

[Markus Popp]

> The column-based privileges are select, update, insert, and references.

The 'references' privilege ist currently unused - it does exist as well as
some other privileges, too. To allow a user to delete records, the delete
privilege is required.

Markus

[Gordon Burditt]

>> The column-based privileges are select, update, insert, and references.

The 'references' privilege ist currently unused - it does exist as well as
some other privileges, too.
There is no *column-based* delete privilege. 'delete' privilege
applies to particular tables.
To allow a user to delete records, the delete
privilege is required.

It is not meaningful to delete a particular column out of a particular
row. You can only delete entire rows.

Gordon L. Burditt

[Markus Popp]

Okey, you won ;-) - I was still a level too high.

Markus