Re: Migrating a MySQL schema with an enum

SQL gurus,

Migrating a MySQL schema with an enum to PostgreSQL,
is there an equivalent type or do I have to declare
another table for "enum" values.

--
Keith Gray

Technical Development Manager
Heart Consulting Services P/L
mailto:keith(at)heart(dot)com(dot)au

Keith Gray wrote:
> SQL gurus,
>
> Migrating a MySQL schema with an enum to PostgreSQL,
> is there an equivalent type or do I have to declare
> another table for "enum" values.

You can use another table, or use CHECK constraints to limit the
possible values.

--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
+ If your life is a hard drive, | 830 Blythe Avenue
+ Christ can be your backup. | Drexel Hill, Pennsylvania 19026

Keith Gray writes:

> Migrating a MySQL schema with an enum to PostgreSQL,
> is there an equivalent type or do I have to declare
> another table for "enum" values.

Generally, you'd use a text field with a check constraint. For example:

CREATE TABLE car (
...
color text check (color in ('blue', 'green', 'yellow')),
...
);

--
Peter Eisentraut peter_e(at)gmx(dot)net

> Keith Gray writes:
>
> > Migrating a MySQL schema with an enum to PostgreSQL,
> > is there an equivalent type or do I have to declare
> > another table for "enum" values.
>
> Generally, you'd use a text field with a check constraint. For example:
>
> CREATE TABLE car (
> ...
> color text check (color in ('blue', 'green', 'yellow')),
> ...
> );

Nope - cos you need 'blue,green' as a value, etc. as well.

I use a varbit field and do the translations from an array of strings to a
bitset and vice versa in the app layer.

Chris

Christopher Kings-Lynne writes:

> > Generally, you'd use a text field with a check constraint. For example:
> >
> > CREATE TABLE car (
> > ...
> > color text check (color in ('blue', 'green', 'yellow')),
> > ...
> > );
>
> Nope - cos you need 'blue,green' as a value, etc. as well.

That's not an enumeration type, that's a set. For set's you create a
separate table.

--
Peter Eisentraut peter_e(at)gmx(dot)net

On Mié 20 Mar 2002 20:41, you wrote:
> SQL gurus,
>
> Migrating a MySQL schema with an enum to PostgreSQL,
> is there an equivalent type or do I have to declare
> another table for "enum" values.

I had to migrate a DB from MySQL to PostgreSQL that had some enum as field
data type (I can't believe that something like that exists), and because it
was something like:

enum('s','n')

I changed it for:

col1 CHAR CHECK (col1 IN ('s','n'))

Which is SQL. :-)

If what is enumerated are numbres, just use INT instead of CHAR.

Saludos... :-)

--
Porqué usar una base de datos relacional cualquiera,
si podés usar PostgreSQL?
-----------------------------------------------------------------
Martín Marqués | mmarques(at)unl(dot)edu(dot)ar
Programador, Administrador, DBA | Centro de Telematica
Universidad Nacional
del Litoral
-----------------------------------------------------------------

On Mié 20 Mar 2002 23:31, you wrote:
> > Keith Gray writes:
> > > Migrating a MySQL schema with an enum to PostgreSQL,
> > > is there an equivalent type or do I have to declare
> > > another table for "enum" values.
> >
> > Generally, you'd use a text field with a check constraint. For example:
> >
> > CREATE TABLE car (
> > ...
> > color text check (color in ('blue', 'green', 'yellow')),
> > ...
> > );
>
> Nope - cos you need 'blue,green' as a value, etc. as well.

That's not how enum() works.

--
Porqué usar una base de datos relacional cualquiera,
si podés usar PostgreSQL?
-----------------------------------------------------------------
Martín Marqués | mmarques(at)unl(dot)edu(dot)ar
Programador, Administrador, DBA | Centro de Telematica
Universidad Nacional
del Litoral
-----------------------------------------------------------------

hi

i'm have installed latest version of postgresql which is 7.2
why i can not use timestamp('now') or time('now') ?
it said : ERROR: parser: parse error at or near "'"

can anyone explain why?
i'm try in 7.1.x. it's works well
did i miss something when installation? is it in new version need somekind
of "plug-in"?

ps: date('now') is work fine

thx in advance

> i'm have installed latest version of postgresql which is 7.2
> why i can not use timestamp('now') or time('now') ?
> it said : ERROR: parser: parse error at or near "'"

Those two words have become a little more reserved. If you go
"timestamp"('now') or "time"('now') it should work.

Even better, I think you can go timestamp 'now' or time 'now' instead
IIRC.

Chris

Martín Marqués wrote:
> On Mié 20 Mar 2002 20:41, you wrote:
>
>>SQL gurus,
>>
>>Migrating a MySQL schema with an enum to PostgreSQL,
>>is there an equivalent type or do I have to declare
>>another table for "enum" values.
>
>
> I had to migrate a DB from MySQL to PostgreSQL that had some enum as field
> data type (I can't believe that something like that exists)

<snip>

another shot at the mysql db.
Please don't forget that PG also has non standard data types
available.

Vinny

On Thu, Mar 21, 2002 at 09:40:42AM -0500, Vincent Stoessel wrote:
> Mart?n Marqu?s wrote:
> >On Mi? 20 Mar 2002 20:41, you wrote:
> >
> >>SQL gurus,
> >>
> >>Migrating a MySQL schema with an enum to PostgreSQL,
> >>is there an equivalent type or do I have to declare
> >>another table for "enum" values.
> >
> >
> >I had to migrate a DB from MySQL to PostgreSQL that had some enum as field
> >data type (I can't believe that something like that exists)
>
> <snip>
>
> another shot at the mysql db.
> Please don't forget that PG also has non standard data types
> available.

Your pique at seeing what you took as an unfair shot at another db caused you
to be blinded to what Martin was pointing out. In this case, MySQL has a
gratutiously non-standard feature: the equivalent CHECK constraint is only
a few more characters, and easier to read (IMHO)

Ross

On Jue 21 Mar 2002 13:02, Ross J. Reedstrom wrote:
> On Thu, Mar 21, 2002 at 09:40:42AM -0500, Vincent Stoessel wrote:
> > Mart?n Marqu?s wrote:
> > >On Mi? 20 Mar 2002 20:41, you wrote:
> > >>SQL gurus,
> > >>
> > >>Migrating a MySQL schema with an enum to PostgreSQL,
> > >>is there an equivalent type or do I have to declare
> > >>another table for "enum" values.
> > >
> > >I had to migrate a DB from MySQL to PostgreSQL that had some enum as
> > > field data type (I can't believe that something like that exists)
> >
> > <snip>
> >
> > another shot at the mysql db.
> > Please don't forget that PG also has non standard data types
> > available.
>
> Your pique at seeing what you took as an unfair shot at another db caused
> you to be blinded to what Martin was pointing out. In this case, MySQL has
> a gratutiously non-standard feature: the equivalent CHECK constraint is
> only a few more characters, and easier to read (IMHO)

Thanks Ross, I was just about to say the same thing. Why had an unstandard
data type, whn you can have it SQL-standard.
I think that the problem MySQL has is CHECK.

Saludos... :-)

--
Porqué usar una base de datos relacional cualquiera,
si podés usar PostgreSQL?
-----------------------------------------------------------------
Martín Marqués | mmarques(at)unl(dot)edu(dot)ar
Programador, Administrador, DBA | Centro de Telematica
Universidad Nacional
del Litoral
-----------------------------------------------------------------