Booleans - Why in Postgres and not in Oracle or Mysql?

-----Original Message-----
From: pgsql-general-owner@postgresql.org [mailto:pgsql-general-
owner@postgresql.org] On Behalf Of CSN
Sent: Thursday, May 05, 2005 11:57 AM
To: pgsql-general@postgresql.org
Subject: [GENERAL] Booleans - Why in Postgres and not in Oracle or

Mysql?

I like Postgres's boolean type -

Me too.

why do you suppose
neither Mysql nor Oracle has bothered to implement it?

Probably they just create a domain using a char which can take on two
values (e.g. 't'/'f' or 1/0). Oracle 10 has a bit data type (which is a
boolean for all intents and purposes):
B.1 BIGINT
B.2 BINARY
B.3 BIT
B.4 BLOB
B.5 CHAR
B.6 CLOB
B.7 DATE
B.8 DECIMAL
B.9 DOUBLE PRECISION
B.10 FLOAT
B.11 INTEGER
B.12 LONG
B.13 LONG RAW
B.14 LONG VARBINARY
B.15 LONG VARCHAR
B.16 NUMBER
B.17 NUMERIC
B.18 RAW
B.19 REAL
B.20 ROWID
B.21 SMALLINT
B.22 TIME
B.23 TIMESTAMP
B.24 TINYINT
B.25 VARBINARY
B.26 VARCHAR
B.27 VARCHAR2

MySql has a partial Boolean implementation. From
http://dev.mysql.com/doc/mysql/en/numeric-type-overview.html:

BOOL , BOOLEAN

These are synonyms for TINYINT(1). The BOOLEAN synonym was added in
MySQL 4.1.0. A value of zero is considered false. Non-zero values are
considered true.

In the future, full boolean type handling will be introduced in
accordance with standard SQL.

Booleans are in the SQL-99 spec.

Probably, MySQL and Oracle will have Boolean types eventually with full
compatibility to the standard.

CSN

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--- Dann Corbit <DCorbit@connx.com> wrote:

why do you suppose
neither Mysql nor Oracle has bothered to implement

it?

Probably they just create a domain using a char
which can take on two
values (e.g. 't'/'f' or 1/0). Oracle 10 has a bit
data type (which is a
boolean for all intents and purposes):

Could a bit handle NULL's though?

CSN

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CSN wrote:

I like Postgres's boolean type - why do you suppose
neither Mysql nor Oracle has bothered to implement it?
Booleans are in the SQL-99 spec.

Fear of breaking old applications

--
Peter Eisentraut
http://developer.postgresql.org/~petere/

On Thu, 2005-05-05 at 15:28, CSN wrote:

--- Dann Corbit <DCorbit@connx.com> wrote:

why do you suppose
neither Mysql nor Oracle has bothered to implement

it?

Probably they just create a domain using a char
which can take on two
values (e.g. 't'/'f' or 1/0). Oracle 10 has a bit
data type (which is a
boolean for all intents and purposes):

Could a bit handle NULL's though?

ISTR there is some debate on whether Booleans should allow NULL and
thats why the boolean type is still in the extended set of sql spec and
not core.

Inceidentally MySQL's boolean is really scary... it's not just than 0 =
false and 1 = true, its 0 = false and (n >= 1) is true. IMHO that
sounds like a recipe for creating subtle bugs.

Robert Treat
--
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