Re: Boolean and Bit

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От Josh Berkus
Тема Re: Boolean and Bit
Дата
Msg-id web-1178138@davinci.ethosmedia.com
обсуждение исходный текст
Ответ на Boolean and Bit  (Keith Gray <keith@heart.com.au>)
Список pgsql-sql
Keith,

> This is a compatibility issue. While I prefer to use
> BOOLEAN, this is SQL3
> and not available on the (unfortunately must use)
> MS-SQL/MSDE platform.
> 
> My options are to use a CHAR field and re-write my code
> for "T" and "F" or
> an int field and re-write my code to use "field=0" and
> "field<>0"

Given that all the MS-SQL BIT field is, is INT1, using INT2
should not be much of a problem.  Go ahead an create a
custom type based on INT2 and add constraints to prevent any
values outside of the range of 0 and 1.

This is where the SQL92 DOMAIN (not, as far as I know,
available in PGSQL) construction would be useful in
PostgreSQL instead of TYPE (Tom?).  The problem with TYPE is
that you theoretically need to define a whole set of
operators for your TYPE, while DOMAIN is a bit simpler.

> I would like to distribute a script (SQL) file to our
> users to update
> databases to new versions... obstacles include
> BOOLEAN/BIT and the 
> inconsistent use of BLOB/MEMO/[long]varchar(4096).

Well, yes.  This is beacause BLOBs are NOT part of the SQL
standard and IMHO a bad idea relationally; thus their
implementation is entirely proprietary to the RDBMS.  The
solution is not to use BLOBs.  

> Distributing schema patches is proving troublesome across
> multiple
> platforms.

Yup.  Yer in for a world of pain, sonny.  Hope you get paid
hourly.

-Josh


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